State OBBBA Conformity Is Fragmenting. Your Provision System Can't See It.

EY's Q3 2026 state tax report shows DC, New York, Pennsylvania, and North Carolina diverging on OBBBA conformity. Here's what it means for your Q4 close.

Editorial source review — November 1, 2026. This machine-generated article has been reviewed, but is not certified accurate. Source-backed corrections are incorporated where established. Other legal, survey and product claims may remain unverified; check applicable primary authorities before relying on a deadline or tax position.

Findings in the original version: the EY alert is a summary with linked detailed analysis. It does not independently establish every state's conformity date, DC emergency-act effect or PA bulletin interpretation.

EY published its Q3 2026 state corporate income and franchise tax roundup on October 13. Four states took positions on OBBBA conformity in the same quarter and reached three different conclusions. If your provision system is pulling a single federal taxable income number and apportioning it across states, you are computing state deferred tax assets and liabilities wrong.

The One Big Beautiful Bill Act passed in July 2025 and created more than a dozen changes to the Internal Revenue Code that have immediate state tax implications. Section 174A restored immediate domestic R&E deductibility. Section 163(j) reverted to the EBITDA-based limitation. Bonus depreciation returned to 100%. Each one triggers a conformity question in every state where you file. Most states did not update their conformity statutes before year-end 2025. They are doing it now — in 2026 — and they are not moving in the same direction. Thomson Reuters described this accurately in September: "Nearly Four Months After OBBBA, States' Corporate Tax Conformity Patchwork Continues to Emerge." That patchwork thickened materially in Q3. Here is what happened and what it means for your year-end close.

The Q3 State Conformity Map Is Broken

The OBBBA conformity map entering Q3 2026 already had meaningful divergence. New York had proposed decoupling language. DC had passed an emergency decoupling act that Congress then attempted to nullify. Pennsylvania's position was unclear. As of the EY Q3 2026 roundup — which covers legislative and administrative activity through September 30 — the picture has gotten substantially more complicated, not simpler.

The core analytical problem is this: state conformity is not a binary yes/no answer. States conform to the IRC as of a rolling date, a fixed date, or selectively by provision. A state that conforms to the IRC as of December 31, 2024 does not automatically adopt OBBBA because OBBBA was enacted July 4, 2025. A state with a rolling conformity date adopts it automatically unless it explicitly decouples. A state with selective conformity that has not updated its statute is in genuine ambiguity. The provision team has to know which conformity model each state uses before they can compute deferred taxes correctly. Most provision systems assume uniform conformity. None of them are right in Q4 2026.

DC: An Emergency Decoupling That Has Already Been Contested Once

The District of Columbia passed emergency legislation on August 13, 2026 that decouples from several OBBBA provisions for tax years 2025 and 2026. The two most significant items: DC retains five-year capitalization and amortization for domestic R&E expenses — the Section 174 treatment that existed before OBBBA — and DC does not adopt the OBBBA change to the Section 163(j) business interest limitation computation. Under DC law, taxpayers must use EBIT rather than EBITDA to compute the 30% interest deductibility limitation.

This is not the first time DC has tried this. Earlier in 2026, the DC Council passed a decoupling bill. Congress passed House Joint Resolution 142 in February 2026 to nullify it. The DC Office of Tax and Revenue told taxpayers to disregard the federal nullification and continue treating DC as decoupled. That dispute has not been fully resolved. The August 13 emergency act is a continuation of the same legal contest between the federal government and the District's tax authority.

For the provision, this means: if you have DC-filing entities, you have at minimum a tax position uncertainty around the Section 163(j) computation. The deferred tax liability for capitalized R&E under federal law does not exist under DC law — that difference needs to be recorded separately in your state provision. And that position is currently subject to a contested legal status that warrants UTP disclosure language. Treating DC as a simple conforming state in your Q4 model is incorrect.

New York: Retroactive Decoupling Plus a Franchise Tax Rate Extension

New York enacted a budget bill earlier in 2026 that took two major actions relevant to the Q4 provision. First, it retroactively decouples from the OBBBA's accelerated deductions for domestic R&E expenses under Section 174A and for qualified production property. The decoupling is retroactive — it applies to tax years beginning on or after January 1, 2025. If your NY entities deducted 2025 domestic R&E immediately under OBBBA and your state provision reflected that, you have a 2025 period adjustment to make.

Second, New York extended the top corporate franchise tax rate for taxpayers with more than $5 million of business income. This is the apportionment-based rate that New York imposes on large corporate taxpayers, and its extension affects the deferred tax rate used to measure all New York temporary differences. If you revalued your New York deferred taxes based on an expected rate reduction that is not coming, that calculation needs to be reversed.

EY reported that penalty and interest relief applies to liabilities arising from the retroactive decoupling — but that relief does not make the underlying provision adjustment disappear. The deferred tax recomputation for New York entities is a Q4 task, not a filing-season task.

Pennsylvania: Explicit Conformity Creates Its Own Deferred Tax Problem

Pennsylvania issued Corporation Tax Bulletin 2026-01 on September 10. It takes the opposite position from New York and DC: Pennsylvania explicitly conforms to IRC Section 163(j) as of December 31, 2024. The OBBBA amendments to 163(j) — specifically the restoration of EBITDA-based computation — do not apply for Pennsylvania corporate income tax purposes.

This sounds like a simpler position — explicit conformity, clear rule — but it creates a different deferred tax problem. Pennsylvania-filing entities that use the federal EBITDA-based 163(j) computation will have different interest deductibility than their Pennsylvania standalone calculation. That delta creates a Pennsylvania-specific deferred tax position. The Philadelphia Business Income and Receipts Tax adds another layer: Senate Bill 146, introduced in the Pennsylvania legislature, would allow Philadelphia to decouple from certain OBBBA provisions when computing BIRT liability. If that bill passes during Q4, your Philadelphia effective tax rate changes mid-period.

Pennsylvania also confirmed rolling IRC conformity for most other provisions — which means OBBBA's bonus depreciation and Section 179 changes do apply in Pennsylvania, just not the 163(j) change. Computing deferred taxes for Pennsylvania-filing entities requires the provision team to hold multiple simultaneous starting points in their head: federal law for depreciation, pre-OBBBA law for interest limitation.

North Carolina and the Pattern That Keeps Repeating

North Carolina decoupled from the federal treatment of domestic R&E expenses under Section 174A during Q3. It did not decouple from bonus depreciation or 163(j). This is the partial-conformity model — and it is the most analytically difficult one to handle in a provision system.

Partial conformity means the state tax base cannot be derived from either the federal taxable income or any single prior-year state calculation. It has to be reconstructed from scratch for each state, with specific adjustments for each decoupled item. North Carolina joins New York, DC, and a growing list of states in taking this partial approach. The pattern is predictable at this point: states want the revenue from keeping R&E costs capitalized, they are willing to adopt the other OBBBA changes that reduce their administrative complexity, and they are making these decisions one provision at a time in the legislative calendar.

The implication for the provision: the number of state-specific R&E temporary differences in your model is growing each quarter. Each new decoupling state creates a standalone deferred tax asset or liability for the R&E costs that are deducted immediately under federal law but amortized over five years under state law. Those assets and liabilities have their own reversal schedules, their own valuation allowance considerations, and their own rate-change sensitivity.

What Your Provision System Needs to See

The provision systems that are struggling with this are the ones built on a single-source federal tax base with state adjustments applied as a percentage. That architecture was defensible when most states had rolling conformity and followed the federal base closely. It is not defensible now. The OBBBA created structural divergence across states that will compound with each legislative session.

The provision system needs to maintain, for each state where you file: the IRC conformity date or mechanism, the specific OBBBA provisions to which the state has decoupled, the temporary difference schedules under state law rather than federal law, and the applicable state rate — including any rate changes like New York's franchise tax extension. That is a data model, not a spreadsheet formula. It requires a knowledge graph layer that tracks state tax law changes as they are enacted and maps them to the specific temporary differences in the provision.

At Clarity Tax, we track state conformity changes in real time. When DC passed its August 13 emergency act, DisclosureIQ flagged every client with DC-filing entities and mapped the R&E and 163(j) impacts to their existing deferred tax schedules. That is the deterministic-first approach applied to state tax: the rule changes, the provision knows it, the exposure is quantified before the next board meeting.

What to Do Monday Morning

Sources

Clarity Tax tracks state conformity changes in real time and maps them to your deferred tax schedules automatically. See how DisclosureIQ handles the OBBBA patchwork at scale.

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