State Conformity to Federal Tax Law: Rolling vs Static vs Selective
Every state with an income tax must decide how much of the Internal Revenue Code it adopts. That decision falls into one of three models: rolling conformity, where the state automatically incorporates all federal IRC changes as they happen; static (or fixed-date) conformity, where the state conforms to the IRC as of a specified date and ignores later amendments until the legislature acts; and selective conformity, where the state adopts the IRC generally but decouples from specific provisions it doesn't want to follow. After the One Big Beautiful Bill Act restored 100% bonus depreciation under IRC 168(k) and made the Section 199A qualified business income deduction permanent, the conformity model your client's state follows determines whether those changes apply at the state level, whether they're delayed, or whether they never arrive at all.
Why Conformity Models Matter Right Now
OBBBA made two changes that affect nearly every business return. First, it restored 100% first-year bonus depreciation under IRC 168(k), reversing the phasedown that had dropped to 40% for 2025. Second, it made the Section 199A QBI deduction permanent, removing the December 31, 2025 sunset. Both changes are governed by Treasury Regulations at Treas. Reg. 1.168(k)-1, 1.168(k)-2, and Treas. Reg. 1.199A-1.
For your clients in rolling conformity states, these federal changes applied the moment the President signed the bill. For your clients in static conformity states, the answer depends on the state's fixed date, and many of those dates predate OBBBA. That gap between federal law and state law creates additional work on every affected return.
The cost adds up fast when you're checking conformity across multiple states. A multi-state client with operations in a rolling state, a static state, and a selective state isn't just one research question. It's three, each with its own depreciation schedule and its own QBI treatment.
Rolling Conformity: Automatic Adoption
Rolling conformity is the simplest model. The state defines its taxable income as federal taxable income (or federal adjusted gross income) and incorporates all IRC amendments automatically. When Congress changes the Code, the state follows without any additional legislation.
Example states: New York, Colorado, Illinois, New Mexico, North Dakota.
New York Tax Law Section 607(a) defines "entire net income" by reference to the IRC, and the state updates that reference in real time. When OBBBA restored 100% bonus depreciation, New York practitioners could apply it on state returns immediately. No waiting for the legislature. No separate calculation.
The upside for practitioners is simplicity. Federal and state depreciation schedules match. The QBI deduction calculation works the same way.
The downside for states is unpredictability. Rolling conformity means the legislature surrenders control over revenue impacts from federal changes. When Congress expands a deduction, the state absorbs the revenue loss automatically.
Static Conformity: Frozen in Time
Static conformity states adopt the IRC as of a specific date and only move that date forward through affirmative legislation. Until the legislature acts, any federal change enacted after the state's conformity date simply does not exist for state tax purposes.
Example states: California (January 1, 2015), Wisconsin (December 31, 2020), Virginia (December 31, 2022), Arizona (January 1, 2023).
California is the most prominent example. CA Revenue and Tax Code Section 17024.5 conforms to the IRC as of January 1, 2015. That date has not moved in over a decade. This means California did not automatically adopt the Tax Cuts and Jobs Act changes, did not automatically adopt the SECURE Act changes, and will not automatically adopt the OBBBA changes to bonus depreciation or Section 199A.
The California Franchise Tax Board publishes a conformity guide covering each federal provision and whether California follows it. Tax Orator has California's conformity publication in its database, alongside 21,900+ documents covering all 50 states. When a client asks whether California conforms to a specific provision, you can pull the state's own published guidance instead of guessing.
The practical impact: if you prepare a federal return claiming 100% bonus depreciation for a California-resident client, you need a separate depreciation schedule for the state return. The state may still use the pre-OBBBA phasedown rules, or it may have its own modified depreciation provisions. Either way, it's not the same number, and you need to track the difference.
Selective Conformity: Picking and Choosing
Selective conformity falls between the other two models. The state generally conforms to the IRC but carves out specific provisions. Some states call these "decoupling" provisions. The state might conform to the IRC as of the current date for most purposes, then explicitly reject bonus depreciation, or cap Section 179 expensing at a lower amount, or decline to follow a specific OBBBA provision.
Example states: Maine, Iowa, Georgia, New Jersey, Minnesota.
Maine is a useful example because it shows how selective conformity plays out in practice. Maine's Department of Revenue has published detailed guidance on its modifications related to bonus depreciation and Section 179 expensing, explicitly decoupling from the federal bonus depreciation rules. Tax Orator indexes five OBBBA conformity documents from Maine: the Commissioner's letter to the Governor, the Governor's Directive, and three Office of Tax Policy analysis reports (the initial report, a draft addendum, and the consolidated final report). These documents walk through exactly how Maine's government analyzed whether to conform to OBBBA's federal changes.
Iowa takes a different approach. The state provides Form IA 101, which lists specific "nonconformity adjustments" taxpayers must make on their state return. If the state decouples from a federal provision, the adjustment appears on that form. Idaho publishes its own conformity guidance document covering how it handles tax reform provisions.
For practitioners, selective conformity is the most research-intensive model. You can't assume the state follows the federal rule, and you can't assume it rejects it. You have to check each provision individually.
State Groupings by Conformity Type
Rather than listing all 50 states (which would be outdated the next time a legislature acts), here's how conformity generally breaks down. These groupings are current as of May 2026, but states change their conformity dates regularly.
Rolling conformity (automatic adoption): New York, Colorado, Illinois, New Mexico, North Dakota, Utah, Kansas, Montana. Practitioners in these states apply OBBBA changes immediately.
Static/fixed-date conformity (legislative update required): California, Virginia, Wisconsin, Arizona, Oregon. Check the state's fixed date before assuming any recent federal change applies.
Selective conformity (provision-by-provision): Maine, Iowa, Georgia, New Jersey, Minnesota, Pennsylvania, Connecticut, Hawaii. Each state decouples from different provisions, so you need to check the specific rule, not just the general conformity posture.
No broad-based income tax: Alaska, Florida, Nevada, New Hampshire (interest and dividends only through 2024), South Dakota, Tennessee (interest and dividends only through 2020), Texas, Wyoming. Washington enacted a 9.9% tax on income above $1 million in March 2026 (SB 6346, collections begin 2029), so its conformity posture will matter once the tax takes effect. For the remaining states in this group, there is no conformity question to answer.
OBBBA Provisions That Trigger Conformity Issues
Two OBBBA changes create the most conformity work for practitioners.
IRC 168(k) bonus depreciation restoration. The federal rules at Treas. Reg. 1.168(k)-1 and 1.168(k)-2 govern bonus depreciation. OBBBA restored 100% first-year depreciation retroactive through the phasedown period. Rolling conformity states follow this automatically. Static conformity states whose fixed date predates OBBBA (like California at January 1, 2015) do not recognize the restoration unless the legislature acts. Selective conformity states may continue to decouple from bonus depreciation entirely, regardless of the federal restoration.
This means a single piece of equipment purchased in 2025 could have three different depreciation treatments: 100% bonus on the federal return, a modified amount on a static conformity state return, and yet another calculation on a selective conformity state return that has its own depreciation cap.
Section 199A permanence. Treas. Reg. 1.199A-1 governs the QBI deduction. OBBBA made Section 199A permanent, removing the scheduled sunset. For rolling conformity states, this is a non-event: the deduction continues with no action needed. For states that never adopted Section 199A in the first place (several static conformity states), making it permanent at the federal level doesn't create a state deduction. The state still doesn't follow the provision.
What This Means for Multi-State Practices
If you serve clients across state lines, conformity research is not optional. A client with a passthrough business operating in New York (rolling), Virginia (static), and Maine (selective) needs three separate analyses. Does New York follow OBBBA? Yes, automatically. Does Virginia? Only if the legislature updated its conformity date past July 4, 2025. Does Maine? Maybe, except Maine specifically decouples from bonus depreciation, so even if it conforms generally, this particular provision may not carry over.
That's three conformity checks, three potential depreciation schedule differences, and three potential QBI deduction variations. On one return.
The practitioners who handle this well are the ones who can access state-specific guidance quickly. Not just the statute text, but the DOR publications, the conformity guides, the nonconformity adjustment forms. Citation-backed research matters here more than anywhere else because you're citing state authority, not just federal authority. Getting the federal answer right and the state answer wrong is a common, expensive mistake.
Staying Current Across 50 States
Conformity dates change every legislative session. A state that conforms to the IRC as of December 31, 2022 today might update to December 31, 2025 next month. Selective conformity states add and remove decoupling provisions regularly.
This is one area where traditional manual research struggles. Checking conformity across even five states means reading five sets of DOR guidance, five sets of conformity publications, and five sets of legislative updates. The comparison of AI tax research tools breaks down how different platforms handle multi-state coverage.
Tax Orator tracks conformity guidance from all 50 states, with over 21,900 documents including state DOR publications, conformity memos, adjustment forms, and legislative analysis documents like the Maine OBBBA conformity package.
For solo practitioners handling multi-state clients, conformity research is where time disappears. Checking one state takes a few minutes. Checking three takes an hour if you're using traditional methods. The right research tool cuts that to minutes, not because it skips the analysis, but because it puts the state's own published guidance in front of you instead of making you hunt for it.
If you're evaluating whether your current research workflow handles state conformity well, start with a real scenario. Take a multi-state client with OBBBA-affected items and time yourself researching the state treatment in each jurisdiction. If it takes more than 10 minutes per state, there's room to improve. Tax Orator's Discovery plan gives you 10 free queries to test with your own questions, or the Solo Practitioner plan at $79 per month covers 200 queries for practices with steady multi-state work.