An All Too Familiar Conformity Issue for Arizona Tax Professionals

“ADOR Outlines Executive Order and 2025 Tax Year Income Tax Forms,” Arizona Department of Revenue mailing list, January 22, 2026

As we prepare for the 2025 filing season, Arizona tax professionals who may be new to the Arizona specific quirks of annual conformity find themselves in a unique procedural posture for filing tax returns. However, as those who been in practice for many years in Arizona knows, a federal bill passing during the year with significant changes that, if adopted in full by Arizona would result in a substantial reduction in revenue, generally means that the conformity answer won’t likely be settled until after the April 15, 2027 unextended filing deadline.

Arizona Department of Revenue and Tax Forms

The Arizona Department of Revenue (ADOR) has issued individual income tax forms for the 2025 Tax Year that assume conformity with federal tax changes and incorporate state-level executive directives before they are officially enacted into law. This presents a technical non-conformity issue. Arizona’s tax law typically references federal values, such as adjusted gross income or itemized deduction computations, based on federal law as it stood on January 1, 2025. However, the federal “One Big Beautiful Bill Act” was not enacted until July 4, 2026, meaning the current ADOR forms anticipate federal law that post-dates Arizona’s current statutory reference date.

The Arizona Department of Revenue (ADOR) conventionally publishes tax forms based on this simplifying assumption, a practice that may seem unconventional to tax professionals outside of Arizona. This is because the state legislature historically does not adopt tax conformity—especially in years with a significant revenue impact—until the final budget bill is passed at the end of the regular legislative session. Based on past experience, this typically occurs well after the April 15 filing deadline. Most often either the Legislature and Governor agree to conform to all federal changes or only fail to conform to a limited number of items, so this default allows returns to be filed in a timely manner while limiting the number of taxpayers that must later amend their returns.

This article outlines the technical guidance provided by ADOR regarding the filing of 2025 returns and analyzes the specific provisions introduced by Governor Hobbs’ Executive Order 2025-15. Practitioners must understand the “file now, potentially amend later” stance taken by the Department and the specific tax relief measures currently embedded in the forms.

The “Presumed Conformity” Approach

Historically, ADOR has issued forms based on the assumption that the Arizona Legislature will conform to Internal Revenue Code (IRC) changes made in the prior year. For the 2025 tax year, this practice has been codified and expanded via Executive Order (EO) 2025-15.

The Department has explicitly stated that the 2025 forms reflect a “regular process of assuming conformity” to the IRC. The primary driver for this early release is the federal enactment of Public Law No. 119-21 (“H.R. 1”) in July 2025. Because Arizona law mandates Federal Adjusted Gross Income (FAGI) as the starting point for state income tax calculations, ADOR determined that failing to update forms to align with federal changes would disrupt the filing process for practitioners and taxpayers alike.

The specific concern cited by the Executive is the standard deduction. Since tax year 2019, Arizona has conformed to the federal standard deduction. The Governor’s office noted that H.R. 1 includes a higher standard deduction for tax year 2025. Without the Executive Order directing ADOR to update the forms to match this federal amount, approximately 90% of Arizona taxpayers (those claiming the standard deduction) would face immediate non-conformity, resulting in potential confusion and administrative rework.

The “Middle Class Tax Cuts Package” (The Governor’s Position)

Beyond standard IRC conformity, the 2025 forms include specific subtractions derived directly from Governor Hobbs’ Executive Order. The EO identifies these as the “Middle Class Tax Cuts Package”.

Practitioners should note that the 2025 forms currently allow for the following five specific provisions:

  1. Increased Standard Deduction: Matching the levels contemplated in H.R. 1,.
  2. Subtraction for Seniors: The EO specifies this as an “additional deduction of $6,000 for Arizonans aged 65 and older”. ADOR guidance confirms this subtraction is present on the released forms.
  3. Subtraction for Qualified Tip Income: Included as a specific line item subtraction,.
  4. Subtraction for Qualified Overtime Compensation: Included to provide relief for hourly workers,.
  5. Subtraction for Qualified Vehicle Loan Interest: This allows for the deduction of qualifying car loan interest,.

Incorporating these specific federal changes into the 2025 Arizona tax forms constitutes a departure from established practice. Typically, a bill solely advancing the Arizona conformity date to January 1, 2026, would not include these items in calculating Arizona taxable income.

Arizona utilizes its own distinct standard deduction, which is similar to, but not identical to, the federal standard deduction as it existed prior to the 2025 Tax Cuts and Jobs Act. Furthermore, the last four provisions listed do not impact federal Adjusted Gross Income (AGI) and are not treated as itemized deductions. Instead, they operate to reduce taxable income in a manner akin to the IRC §199A qualified business income deduction, which is never permitted for Arizona tax purposes. Their function is exclusively to be used in calculating federal taxable income pursuant to IRC §83.

It is important to recognize that while H.R. 1 reduced taxes for top earners and altered federal credits, ADOR’s forms only adopt the changes affecting FAGI and the specific relief measures directed by the Governor. Federal credits found in H.R. 1 that do not impact FAGI are not included on the Arizona forms.

Filing Guidance and Amendment Risks Given Subsequent Legislative Action

The most pressing question for CPAs is procedural: Should we hold returns until the Legislature convenes in January 2026?

ADOR’s guidance is unequivocal: No. Taxpayers should not wait to file.

However, this creates a distinct risk of bifurcation between the Executive’s forms and the Legislature’s eventual statutes. If the Legislature passes a conformity bill consistent with the forms released by ADOR, no further action will be required.

Conversely, if the Legislature does not approve these specific provisions, or passes a conformity bill that differs from the Governor’s EO (such as the provisions contemplated in SB 1106), taxpayers who utilized these subtractions may need to file amended returns.

The Legislature has passed a conformity bill that differs significantly from the Governor’s proposed Middle Class Tax Cut bill. The Governor subsequently vetoed the passed bill, and an override is highly improbable because the vote was strictly partisan. This situation arose following the issuance of the EO.

Penalty Relief Safe Harbor

Anticipating the potential need for mass amendments, ADOR has established a safe harbor for taxpayers caught between the Executive Order and Legislative action.

If a taxpayer files a 2025 return utilizing the provisions in the current forms, and those provisions are later deemed inconsistent with the final law passed by the Legislature:

  • ADOR will provide specific guidance on how to amend.
  • Taxpayers will not be subject to penalties or interest, provided the amended return is filed by October 15, 2027.

Conclusion

The release of the 2025 forms represents a strategic administrative move to prevent the “costly rework” of millions of returns regarding the standard deduction. However, by including the specific “Middle Class Tax Cuts” (senior, tip, overtime, and vehicle loan subtractions) prior to legislative approval, the Department has shifted the burden of monitoring legislative developments to the practitioner community.

We are advised to prepare 2025 returns using the forms as issued, taking advantage of the increased standard deduction and new subtractions where applicable. However, client communication letters should likely include a caveat regarding the pending legislative session and the remote possibility of a required amendment should the Legislature reject the Governor’s tax package.

Key Takeaway:

Per the Department of Revenue, tax professionals should:

  • File with Current Forms: Ensure all filings utilize the most up-to-date forms.
  • Monitor Legislation: Closely watch the 2026 Legislative Session for changes to Arizona’s conformity related to H.R. 1 and any subtraction modifications proposed by the Governor.
  • Utilize Safe Harbor: Rely on the October 15, 2027, safe harbor provision, which is anticipated to be necessary in the likely case where the final legislation differs from the Governor’s Middle Class Tax Cuts Proposal.

Prepared with assistance from NotebookLM.

The Statutory Void: How Sirius and Norwood Could Combine to Create Automatic SE Tax Liability for LLC Members

The Fifth Circuit’s recent decision in Sirius Solutions, L.L.L.P. v. Commissioner, No. 24-60240 (5th Cir. 2026), creates a strict textualist framework for the self-employment (SE) tax exclusion under I.R.C. § 1402(a)(13) for cases that would be appealed to the Fifth Circuit Court of Appeals.

While this decision provides a safe harbor for state-law limited partners, it simultaneously dismantles the functional analysis test that Limited Liability Company (LLC) members have historically relied upon to claim the exclusion. When the strict textual definition of “limited partner” adopted in Sirius is combined with the Tax Court’s precedent in Norwood v. Commissioner, a dangerous syllogism emerges: LLC members, lacking the specific state-law title required by the Fifth Circuit, may default to the general rule of inclusion regardless of their participation levels.

The General Rule of Inclusion: The Norwood Principle

To understand the risk posed by Sirius, one must first revisit the baseline established in Norwood v. Commissioner, T.C. Memo 2000-84. In that case, the Tax Court addressed the SE tax liability of a general partner in a medical supply partnership who spent only 41 hours on partnership matters during the tax year. The taxpayer argued that because his interest was passive, his distributive share should be exempt from SE tax.

The Tax Court rejected this argument, establishing a bright-line rule: unless a partner falls within the specific statutory exception for limited partners, their distributive share of trade or business income is subject to SE tax under Section 1402(a). The court held that the taxpayer’s “lack of participation in or control over the operations of [the partnership] does not turn his general partnership interest into a limited partnership interest”.

Crucially, Norwood established that for partners falling outside the specific Section 1402(a)(13) exception, economic reality regarding participation is irrelevant. The court stated: “That petitioner spent a minimal amount of time engaged in the operations of [the partnership] is irrelevant to this determination… [The distributive share is] subject to the taxes imposed by section 1401 on self-employment income… regardless of whether [the partner’s] involvement is passive or active”.

The Sirius Trap: Narrowing the Exception to State-Law Labels

Prior to Sirius, LLC members navigated the Norwood inclusion rule by arguing that, functionally, they occupied a position analogous to limited partners. However, the Fifth Circuit’s decision in Sirius Solutions ostensibly forecloses this “functional equivalent” argument by insisting on a strict adherence to the text of the 1977 statute.

In Sirius, the Fifth Circuit held that the “limited partner” exception applies only to a specific legal status. The Court declared: “When § 1402(a)(13) says ’limited partner,’ it is referring to a limited partner in a state-law limited partnership that has limited liability”. The opinion emphasizes that the “touchstone of a ’limited partner’ in 1977 was limited liability”, but inextricably links this liability protection to the specific entity format of a limited partnership.

While the Sirius court noted in a footnote that “we do not discuss whether members of another entity, such as an LLP or LLC, may also qualify for the limited partner exception”, the logic of the opinion presents a severe obstacle for LLC members. The Court expressly rejected the Tax Court’s approach of inquiring into the “functions and roles” of the partners. Instead, the Fifth Circuit vacated the lower court’s decision because it relied on an “erroneous passive investor rule”.

The Intersection: Why LLC Members May Be Left with No Defense

The combination of Norwood and Sirius leaves LLC members in a statutory void.

First, under Sirius, an LLC member cannot claim the Section 1402(a)(13) exclusion based on the plain text. An LLC member is not a “limited partner in a state-law limited partnership”. The Norwood court explicitly addressed the necessity of proper form, stating: “A limited partnership must be created in the form prescribed by State law”. Since an LLC is not a limited partnership under state law, the member fails the threshold definition established by the Fifth Circuit.

Second, the “functional analysis” escape hatch has been welded shut. In the past, an LLC member might have argued, “I act like a limited partner, so treat me as one.” However, Sirius explicitly condemns the IRS and Tax Court for applying a test that balances an “infinite number of factors in performing its ’functional analysis test’”. If the Fifth Circuit refuses to look at the “functions and roles” of a partner to grant the exclusion to a state-law limited partner, it is difficult to see how they would apply a functional test to grant the exclusion to an LLC member who lacks the requisite statutory title.

The Consequence: Irrelevance of Participation Level

If an LLC member cannot qualify as a “limited partner” under the Sirius definition, they revert to the general rule of Section 1402(a). Here, Norwood dictates the outcome.

In Norwood, the court held that because the taxpayer was not a limited partner, his income was subject to SE tax “regardless of whether [his] involvement is passive or active”. The court explicitly stated that the “passive activity rules under section 469 have no application in this case” regarding SE tax liability.

Norwood based its decision on the logic that the general rule of the first paragraph of IRC §1402(a) tells us partners pay self-employment tax on income from a trade or business carried on the partnership. It states:

(a) Net earnings from self-employment. The term “net earnings from self-employment” means the gross income derived by an individual from any trade or business carried on by such individual, less the deductions allowed by this subtitle which are attributable to such trade or business, plus his distributive share (whether or not distributed) of income or loss described in section 702(a)(8) from any trade or business carried on by a partnership of which he is a member (emphasis added);…

To avoid this result, a partner needs to look to the exceptions found enumerated in the remainder of IRC §1402(a), of which IRC §1402(a)(13) provides the limited partner exception found in this case.

While the Tax Court in Renkemeyer, Campbell & Weaver, LLP v. Commissioner, 136 TC 137, effectively reversed the Norwood analysis as applied to LLCs, the Fifth Circuit panel clearly states that the functional analysis the court turned to in Renkemeyer is not an appropriate inquiry to define the “limited partner, as such” in IRC §1402(a)(13).

Therefore, applying the Sirius logic to an LLC member results in the following position:

  1. The LLC member is not a “limited partner” because they are not in a state-law limited partnership.
  2. The LLC member cannot use a “functional analysis” to prove they are a limited partner, as that test is erroneous.
  3. Without the Section 1402(a)(13) exclusion, the member is subject to the general rule of Section 1402(a).
  4. Under the general rule (Norwood and the plain text of IRC Section 1402(a)’s first paragraph), the member’s distributive share is fully subject to SE tax, even if they spent zero hours working for the entity.

Conclusion

While Sirius Solutions is a victory for traditional limited partnerships, it creates a high-stakes environment for LLCs electing partnership taxation. By defining “limited partner” strictly by reference to state-law limited partnerships and rejecting functional inquiries, the Fifth Circuit may have inadvertently subjected all LLC members to the Norwood regime: automatic SE tax liability on all trade or business income, regardless of whether the member is a passive investor or an active manager. As the Sirius court noted, “state law creates legal interests… but the federal statute determines when and how they shall be taxed”. Without the specific state-law interest of a “limited partnership,” LLC members currently lack a judicially recognized shield against self-employment tax in the Fifth Circuit.

Prepared with assistance from NotebookLM.

Arizona Proposed Tax Conformity and Reform: A Technical Analysis of HB 2153 and SB 1106

The Arizona Legislature is currently moving two identical bills, HB 2153 and SB 1106, which propose substantial modifications to the Arizona Revised Statutes (A.R.S.) regarding income taxation in reaction to the enactment of the One Big Beautiful Bill Act. But despite rapid movement this week, it make take quite a while before we get a complete answer to how Arizona will deal with conformity this year.

While introduced separately, the legislature intends to merge these provisions into a single enactment. The legislation updates Arizona’s conformity date with the Internal Revenue Code (IRC), overhauls the standard deduction calculation, and introduces significant new subtractions from gross income for retirement and labor-related income. However the proposal would add a new nonconformity provision related to itemized deductions for state and local taxes.

While the bill is likely to receive approval from both the House Ways and Means Committee and the Senate Finance Committee in a rare joint committee meeting on January 14, the Arizona Capitol Times reported on January 13 that the bill faces a likely veto when it arrives at the Governor’s desk, while the publication also reported Senate President Warren Petersen stated the bill should arrive on her desk in days.

The Governor does not want to deal with conformity to provisions other than the ones she discussed in her Executive Order released in November until an agreement is reached on the budget for this session. So both the Executive Order and this bill appear to be opening proposals in what seems likely to become an extended battle over budget issues this session.

Even if the bill is vetoed, it is likely that eventually the parties will agree to some form of compromise that includes many of these details, so it is helpful to understand what is in this bill. Just don’t be surprised if we don’t get a bill passed and signed into law until well after the April 15 deadline.

Technical Analysis of the Bill

The following technical analysis details the additions, deletions, and modifications contained in the legislation.

I. Internal Revenue Code Conformity (A.R.S. §§ 42-1001, 43-105)

The legislation updates the definition of the “Internal Revenue Code” for Arizona income tax purposes.

  • Updated Reference Date: For taxable years beginning from and after December 31, 2025, the definition of the IRC is updated to mean the Code as in effect on January 1, 2026.
  • Retroactive Provisions: The bills incorporate provisions that became effective during 2025 with the specific adoption of their retroactive effective dates.
  • Historical Conformity: The bills strike out the specific conformity definition for the 2014–2015 period (Subsection K), effectively rolling the historical window forward.

II. Standard and Itemized Deductions (A.R.S. §§ 43-1041, 43-1042)

Perhaps the most structural change involves the decoupling of the Arizona standard deduction from fixed state-statutory dollar amounts.

A. Standard Deduction Coupling (A.R.S. § 43-1041(A))

Practitioners should note that the specific statutory amounts (e.g., $12,200 for single filers) and the accompanying inflation adjustment mechanisms have been deleted.

Instead, the Arizona standard deduction is now statutorily defined as “the amount of the federal basic standard deduction determined pursuant to section 63 of the internal revenue code for the taxpayer’s filing status”. This creates an automatic lockstep with federal inflation adjustments, removing the need for separate state-level inflation calculations previously mandated under the now-repealed Subsection H.

B. Charitable Contribution Adjustment (A.R.S. § 43-1041(H))

For taxpayers electing the standard deduction, the “charitable add-on” calculation (the additional amount allowed beyond the standard deduction) changes significantly for taxable years beginning from and after December 31, 2025:

  • Old Law: 25% of total charitable deductions allowed, with the percentage annually adjusted by a factor determined by the rate of inflation.
  • New Law: The add-back is equal to 100% of the taxpayer’s charitable contributions as defined in IRC § 170©, but it is subject to a strict statutory cap:
    • $1,000 for single or married filing separately.
    • $2,000 for married couples filing jointly.

C. Itemized Deduction for SALT (A.R.S. § 43-1042(D))

A new provision is added regarding the deduction for state and local taxes (SALT). In lieu of the federal itemized deduction amount allowed under IRC § 164(b)(7), an Arizona taxpayer may deduct up to $10,000 of that amount for state and local taxes. If the bill is enacted into law, Arizona is effectively keeping the “old law” (TCJA) version of the state and local tax deduction, deciding not to conform to the temporary higher deduction allowed on the federal return.

III. Subtractions from Gross Income (A.R.S. §§ 43-1022, 43-1030)

The legislation introduces several new subtractions from Arizona gross income, generally effective for taxable years beginning from and after December 31, 2024. These provisions implement two of the four deductions added to IRC §63 available regardless of whether or not a taxpayer itemizes deductions, but which do not reduce a taxpayer’s federal adjusted gross income. The law provides a substitute for one other of the deductions and quietly declines to adopt the fourth.

A. Labor and Compensation

The two federal Section 63 deductions proposed for adoption into Arizona tax law pertain to compensation.

  • Qualified Tips: Taxpayers may subtract the amount of qualified tips received that are deducted under IRC § 224. (ARS §43-1022(31))
  • Overtime Compensation: Taxpayers may subtract qualified overtime compensation deducted under IRC § 225. (ARS §43-1022(32))

B. Retirement Income (A.R.S. §§ 43-1022(36) and 43-1030)

The bills introduce a complex subtraction matrix for retirement income involving Roth IRAs and pension distributions.

  1. Roth IRA Contributions: A subtraction is allowed for contributions to a Roth IRA (IRC § 408A) made during the taxable year, provided they were not deducted from federal AGI.
  2. Pension/Retirement Distributions (New § 43-1030): Taxpayers aged 60 or older may subtract distributions from qualified pension or retirement accounts.
  3. Aggregate Limits: The combined subtraction for Roth contributions and pension distributions is capped at:
    • $6,000 for single/head of household/MFS.
    • $12,000 for married filing joint.
  4. Means Testing (Phase-out): The subtraction under § 43-1030 (distributions) is reduced by 6% of the amount the taxpayer’s Arizona gross income exceeds:
    • $75,000 (Single/HOH/MFS).
    • $150,000 (MFJ).

This appears to be in lieu of Arizona adopting the over 65 subtraction that the Governor had proposed in her Executive Order.

C. No Tax on Car Interest Deduction Not Adopted

The bill contains no text related to the no tax on car interest deduction added as part of the One Big Beautiful Bill, which serves to decouple Arizona’s taxable income computation from this federal provision.

Arizona tax law starts with federal adjusted gross income and allows itemized deductions by reference to the federal itemized deductions, which means simply updating the IRC conformity date would not bring in a provision that allows a deduction solely in the computation of taxable income as part of IRC §63, such as the deduction for qualified business income under IRC §199A.

So by its silence on the issue, the bill provides that Arizona law will not conform to the federal deduction for certain interest paid to acquire a qualified vehicle.

D. Family and Education

  • Dependent Care: Taxpayers may subtract child and dependent care expenses (IRC § 21) that exceed the federal credit amount received. (ARS §43-1022(34))

  • Adoption Costs (Post-2025): For taxable years beginning after December 31, 2025, the subtraction limit for adoption costs increases from $3,000 to:

    • $5,000 (Single/HOH).
    • $10,000 (MFJ).

    This provision is already part of Arizona tax law, enacted in 2025’s session to take into account the expiration of a higher temporary increase in the allowable adoption expense.

  • 529A/530A Distributions: A subtraction is added for distributions from accounts established pursuant to IRC § 530A (Trump Accounts). (ARS §43-1022(33))

IV. Credits and Other Provisions

A. Dependent Tax Credit (A.R.S. § 43-1073.01)

The bills amend the dependent tax credit amounts. For dependents under seventeen years of age, the credit increases from $100 to $125. The credit for dependents 17 and older remains $25. The phase-out thresholds remain unchanged.

B. Scholarship Granting Organizations (New Chapter 18)

The legislation adds Chapter 18, titled “Scholarship Granting Organizations”.

  • Federal Election: Arizona elects to participate in the federal tax credit established by IRC § 25F.
  • Certification: The Department of Revenue must certify SGOs that meet IRC § 25F requirements.
  • Effective Date: Participation and scholarship issuance under this chapter begin for taxable years from and after December 31, 2026.

V. Summary of Effective Dates

  • Retroactive to Tax Years Beginning After Dec 31, 2024:
    • New subtractions for tips, overtime, dependent care, and retirement (Roth/Pension).
    • IRC Conformity update (Jan 1, 2026 reference).
    • Standard Deduction coupling to IRC § 63.
  • Effective for Tax Years Beginning After Dec 31, 2025:
    • Charitable contribution standard deduction adjustment.
    • Revised adoption cost subtraction.
    • IRC § 530A (Trump Accounts) (This is the practical effective date, as federal law does not allow any funds to be deposited into a Trump account until July 4, 2026, thus no distributions are possible before that date. Technically this provision takes effect for tax years beginning after December 31, 2024 but it simply could not apply to 2025 returns.)
  • Effective for Tax Years Beginning After Dec 31, 2026:
    • Scholarship Granting Organization provisions. (Another practical effective date exists, as the related federal tax credit will not take effect until 2027. Technically, all of these provisions are effective immediately, with the exception of ARS §43-1803, which pertains to organizations issuing SGO scholarships.)

Prepared with assistance from NotebookLM.

Sometimes Memorization Just Ain’t Enough (With Apologies to Patty Smyth for Borrowing Her Title)

In a recent article published by Futurism, Jad Tarifi, the founder of Google’s inaugural generative AI team, posited a cautionary stance regarding careers in law and medicine, asserting that these professions primarily entail the memorization of information. This assertion prompted a critical examination of prevalent misconceptions concerning the true nature of knowledge and skill acquisition within these domains.

A compelling illustration of this misunderstanding is evidenced by the consistent erroneous responses from three distinct AI large language models (LLMs) when queried about specific provisions within the One Big, Beautiful Bill Act (OBBBA) designed to reduce an individual’s adjusted gross income. As I documented in a prior blog entry, I, a certified public accountant (CPA) without additional legal training, and certainly not possessing comprehensive recall of the entire OBBBA, was immediately able to identify the flaw in the models’ conclusions. This occurred despite the theoretical premise that these models “knew” the entirety of the Internal Revenue Code (IRC), along with all pertinent binding guidance, and had unfettered access to the complete legislative text that modified the aforementioned law.

Within tax law, rote memorization has never been, nor will it ever be, the sole method for ascertaining legal principles and their application. Instead, a meticulous reading of the law is imperative, necessitating careful attention to its enumerated items, cross-references, and the subsequent tracing of those references (which may lead to further cross-references) to construct a comprehensive understanding of the statute. Furthermore, the process involves distinguishing unambiguous statutory provisions, which dictate a singular interpretation, from those exhibiting ambiguity, which require interpretation. This interpretive process relies upon established canons of statutory construction developed over time.

Subsequent to this initial statutory analysis, the practitioner must then explore other existing interpretive binding official guidance, assess whether the law has undergone changes since such guidance was issued, and finally, consult expert discussions from third-party sources and non-binding official guidance. This comprehensive approach yields potentially supportable interpretations of the matter at hand, alongside an assessment of the likelihood that any given interpretation would ultimately be accepted by an IRS agent, an appellate conferee, or the highest court to which the case might escalate.

The fundamental flaw in the analyses provided by ChatGPT, Gemini, and BlueJ in this instance was their failure to commence with an isolated examination of the law. Instead, they prematurely resorted to other sources, neglecting to analyze the memorized legal text and the legislative amendments in isolation. Moreover, it remains unclear whether such isolated analysis is truly feasible for these models given their operational paradigms.

As previously detailed, the OBBBA provisions concerning the exemption of tips, overtime pay, and car loan interest from taxation were appended as deductions to Section 63 of the IRC. This classification renders them deductions taken along with either the standard deduction or itemized deductions in computing taxable income, rather than deductions that reduce adjusted gross income. As elaborated upon in the earlier article, deductions utilized in the computation of adjusted gross income would be allocated to Section 62.

While the models had purportedly memorized the entire structure of the IRC, theoretically imparting this knowledge, they failed to undertake the crucial step that tax CPAs and attorneys should perform at this juncture: consulting the statutory text and following cross-references to gain an initial understanding of the IRC’s provisions as amended pertaining to this issue. Instead, they were diverted by other related information contained within their models and acquired from the web during data updates to fill in for developments taking place after the end of time covered by their training. This data included articles quoting Congressional sources that correctly noted these items were deductible regardless of whether a taxpayer itemized deductions. Furthermore, the training data encompassed years of articles that referred to various prior specific items deductible irrespective of itemization as “above the line” deductions. Their data also indicated that “above the line” signified a deduction used in computing adjusted gross income. None of this memorized data was factually incorrect, though much of it proved irrelevant in this specific context.

Consequently, the models quickly identified a high correlation between the terms “deductible even if the taxpayer does not itemize deductions” and a deduction being categorized as “above the line,” as well as a nearly one-to-one correlation between a deduction being referred to as “above the line” and its use in computing adjusted gross income. Again, all of this derived from the memorized information was accurate.

However, at this juncture, the analysis fell apart due to an incorrect inference. The models utilized all data indicating these deductions were available to both itemizing and non-itemizing taxpayers (which was entirely correct) to infer that these deductions were “above the line” and utilized in computing adjusted gross income (absolutely not correct). This inference was reinforced by the historical commentary present within their vast memorized data. Nevertheless, it was an inference that proved completely erroneous.

The question then arises: why did the models’ access to more current sources not challenge their conclusions? This highlights the fallibility of many human authors who were expeditiously producing commentary on the bill. Numerous such articles, some originating from highly reputable sources, incorrectly labeled these provisions as “above the line” deductions.

While the precise reasons for these authors’ misclassification remain speculative, it appears evident that they did not base their initial articles on a direct analysis of the bill itself and the Internal Revenue Code for this issue. It is plausible that many made the same inference that the LLMs derived from their extensive memorized data—namely, that historically, Congress had enacted provisions for items deductible even without itemization as deductions used to compute adjusted gross income. Others, encountering previously published articles making the claim that these deductions reduced adjusted gross income, simply relied upon those sources. Furthermore, I suspect that some authors, operating under time constraints, posed the question to LLMs, which, based on their initial model assumptions, provided the erroneous result.

In any event, the articles discovered by the LLMs analyzing the law served to corroborate their models’ initial assumptions, which were rooted in their extensive memorized data, thereby creating a significant feedback loop.

My approach to the new legislation mirrored that of previous laws, with the notable addition of Google’s NotebookLM, an AI application primarily reliant on user-provided sources. The notebook I established contained exclusively the tax provisions of the statute. As I systematically reviewed each section of the bill, I utilized NotebookLM to generate summaries of the respective sections, while simultaneously conducting my own independent review to ensure comprehensive understanding and prevent oversight during rapid analysis of the law.

NotebookLM’s analysis was largely confined to the provided document, offering little beyond the assertion that each provision modified Section 63 since that was all that was available to the application. Consequently, I cross-referenced Section 63 to ascertain the specific implications of such modifications. As I knew Congress had, on a rare occasion, introduced an additional “below the line” deduction by placing it in this Section, accessible regardless of whether a taxpayer itemized deductions. They had decided to do this multiple times in the new bill.

A precedent for such a deduction can be found in the Qualified Business Income (QBI) Deduction under IRC §199A, enacted by the Tax Cuts and Jobs Act of 2017. This provision has remained in effect and its application was extended as part of the OBBBA.

Posing inquiries to the models regarding the placement of these deductions within Section 63, akin to the QBI deduction in 2017, frequently resolved the models’ prior limitations. This shift in focus directed their attention to articles detailing that specific deduction and highlighting the impact of its placement in Section 63 rather than Section 62. The models subsequently confirmed that the bill text indeed added these deductions to Section 63 and, likely drawing from the newly focused articles, concluded that these deductions do not reduce adjusted gross income.

Even if their approach remained flawed, they did finally arrive at a correct solution.

I am not an attorney and do not claim to be one. However, I would be astonished if similar problems didn’t frequently emerge when parties depend on LLMs for tasks typically handled by law students who would become attorneys, whom Mr. Tarifi suggests should discontinue their legal studies.

Mr. Tarifi undoubtedly possesses far greater knowledge of LLMs and AI than I ever will. Yet, I question whether proponents of AI solutions truly grasp the issues they aim to resolve, or if they merely presume to understand them. The immediate availability of the entire IRC and all supporting documentation within an LLM’s model is genuinely incredibly useful and will revolutionize our approach to tax research and analysis. Nevertheless, I hope I have demonstrated how mere rote memorization is insufficient to perform the job being done today—nor do I observe signs that newer models are progressing beyond memorization to conduct a comprehensive analysis of new laws and developments.

Large Language Models (LLMs) represent a significant advancement that professionals in tax practice must comprehend to maintain relevance. However, similar to the introduction of computers in the 1960s and 1970s and subsequent machine learning enhancements beyond initial automation of routine preparation tasks, LLMs are not anticipated to be the technology that renders tax professionals obsolete.

An Interesting Error from LLMs in Tax Research That Does Not Seem to Be a Hallucination

I was experimenting with three LLMs on a tax research issue recently. I asked them to identify deductions newly available to individuals without a business or rental activity that are deductible in computing adjusted gross income (AGI).

ChatGPT, Gemini, and BlueJ (a paid service for tax professionals) all identified the following:

  • No tax on tips
  • No tax on overtime
  • No tax on interest on car loans

As I’ll show, this answer is wrong. But first, consider this: they all arrived at the same incorrect answer. While we know that LLMs can hallucinate, this isn’t likely a hallucination (an answer created from thin air). If all three models were hallucinating, they would be highly unlikely to invent the exact same error.

The key to the error lies in the distinction between IRC §62 and §63. If you’ve taken my course on the OBBBA, you’ll recall I noted that these specific deductions are routed through §63 (computation of taxable income), not §62 (computation of adjusted gross income). The most well-known §63 deduction is the QBI deduction under §199A-it reduces taxable income on Form 1040 but does not reduce AGI. Because it doesn’t reduce federal AGI, it also doesn’t reduce Arizona taxable income, a crucial point for us here in Arizona.

So, how did all three AIs get the same wrong answer? It’s simple: a large number of human authors, whose material was used in the models’ training data or accessed via web searches, made the same mistake. Because these new deductions were touted as being available even to non-itemizers, many authors assumed they were “above-the-line” deductions and described them as such. However, a review of the statute makes it clear: the OBBBA added these provisions to §63 but made no change to §62.

It’s true that the LLMs didn’t consult the text of the law; they don’t perform legal analysis. Rather, they synthesize the analysis that others have prepared and published, giving extra weight to “high-quality” sources. In this case, a large percentage of human analysts made the same mistake.

There are understandable reasons for this. Bill proponents repeatedly noted the deductions were available even if a taxpayer did not itemize. Many general-purpose financial publications quickly released articles stating these deductions were “above the line.” They presumably equated being able to take a deduction without itemizing with it being an “above-the-line” deduction-an association that was generally, but not always, true before the TCJA and OBBBA.

From personal experience, I know producing an analysis of a new tax bill is done under extreme pressure. Reading federal legislation is messy; the bill only shows the amendments, not the law in its final, consolidated form. It’s easy to miss the significance of a deduction being added to §63 instead of §62.

This distinction is critical because AGI impacts numerous calculations. For states like Arizona that start with federal AGI, these deductions won’t reduce state taxable income. Furthermore, AGI affects tax thresholds (like phase-outs and deduction floors) and even non-tax items like the IRMAA calculation for Medicare premiums.

The takeaway is that relying on a human-written analysis is no guarantee of correctness, either. I have sat through continuing education webinars on the OBBBA that contained this exact error. At this point, the error is so common that it has likely “infected” other human authors, who repeat it after hearing it from multiple sources.

I fully understand how this error was made and could easily have made the same mistake myself (and have likely made other mistakes).  But unless you are working directly from source materials you have to always remember that there could be flaws in the analysis you are reading-and sometimes these errors become self-reinforcing when authors have seen or read previous analyses.