Where can one find an up‑to‑date, state-by-state table of IRC conformity methods for individual income tax (rolling/static/selective)?
Executive summary
A single, up‑to‑date state-by-state table of how each state conforms to the Internal Revenue Code (rolling, static/fixed-date, or selective) is published and maintained by major tax organizations and firms—most notably the AICPA’s conformity map, the Tax Foundation’s state-conformity research, and COST’s state IRC conformity chart—while frequent, state‑level updates appear via big accounting firms and state revenue departments and must be checked for late-breaking changes [1] [2] [3]. No single private resource is legally authoritative; the definitive source for any state’s current position remains that state’s statute and revenue department guidance, particularly because post‑OBBBA legislative moves and emergency decouplings have been common [4] [5].
1. Where to start: AICPA’s map and COST’s chart — concise, visual snapshots
For a ready, downloadable table or map that explicitly categorizes states by conformity method, the AICPA provides a public “Map of States’ Conformity to the Internal Revenue Code (IRC)” intended for practitioners and taxpayers, which serves as a practical first stop [1]; complementing that, the Council On State Taxation (COST) published an IRC Conformity chart (titled “IRC Conformity as of October 31, 2025”) that lays out state positions and recent changes in a spreadsheet/PDF format useful for state‑by‑state comparison [3].
2. Authoritative interpretive reporting: Tax Foundation and expert analyses
The Tax Foundation publishes accessible research explaining the mechanics and counts—such as how many states use rolling versus static conformity and which are selective—and offers policy context about what each approach means for taxpayers and state revenues; their work also tracked shifts after the OBBBA and quantified the potential fiscal impacts on states [2] [4]. For journalists and analysts, Tax Foundation pieces are valuable because they synthesize statutory differences into a single interpretive framework rather than merely listing dates [2] [4].
3. Real‑time changes: accounting‑firm trackers and state advisories
Because many states moved quickly after the One Big Beautiful Bill Act—decoupling, pausing rolling conformity, or advancing conformity dates—large accounting and consulting firms (RSM, Grant Thornton, Plante Moran, Aprio, Wipfli, etc.) have been publishing frequent state update trackers and alerts that capture emergency legislation, guidance, and agency notices that static maps may lag in reflecting [6] [7] [8] [9] [10]. These practitioner alerts are indispensable for near‑term compliance questions, and examples include Michigan’s hybrid option and state decouplings described in firm alerts [7] [11].
4. Why no single “official” table is enough: statutes, agency guidance, and OBBBA fallout
Even the best compiled tables are snapshots: states adopt static dates, roll forward automatically, or selectively pick code sections, but they also routinely “decouple” from specific federal provisions for fiscal or policy reasons—moves that can be temporary, emergency, or legislative—so checking the underlying statute or departmental guidance is essential for legal certainty [12] [6]. The OBBBA triggered especially rapid and uneven state responses, producing frequent reversals and special rules (for example, temporary suspensions of rolling conformity in some jurisdictions), which means a practitioner should corroborate any secondary table against the state source [4] [3] [5].
5. Recommended workflow to get an accurate, up‑to‑date table
Begin with the AICPA map for a quick national overview and download the COST PDF for a detailed, dated chart [1] [3], cross‑check policy context from the Tax Foundation [2] [4], then confirm any state listed as changing its approach by reading that state’s statute and the department of revenue guidance or recent firm advisories (RSM, Grant Thornton, Plante Moran, Aprio) because these capture emergency or retroactive decouplings stemming from recent federal legislation [6] [7] [8] [9]. Where variation exists among secondary sources, prioritize the state statute/agency notice; where speed matters, use firm trackers to flag likely changes and then confirm at the state level [11] [5].