Which states specifically use rolling conformity and which use static conformity for individual income tax as of 2026?
Executive summary
Two consistent facts emerge from recent reporting: states adopt one of three approaches—rolling conformity, static (fixed-date) conformity, or selective/code-specific conformity—and the country is roughly split between rolling and static approaches, with the District of Columbia counted among rolling states in most analyses (reported counts cluster around 18 states + DC using rolling conformity and roughly 18–19 states using static conformity) [1] [2] [3] [4] [5]. However, the publicly provided sources do not contain a single authoritative, source-level, state-by-state list for 2026; coverage instead reports totals and gives examples of specific states that have acted one way or another, so a fully enumerated list cannot be produced from the materials provided here without consulting the underlying tables or state statutes [1] [2] [5].
1. What the core reporting actually says about the split
Multiple tax-policy outlets and practitioners repeatedly state that roughly eighteen states plus the District of Columbia use rolling conformity for individual income tax while a similar number of states use static or fixed-date conformity, with a handful of states practicing selective or partial conformity [1] [2] [3] [4] [5]. Those headline counts recur across independent summaries because rolling conformity—automatic adoption of amendments to the Internal Revenue Code—has been a central point of debate since major federal tax changes, and analysts tracked which states will automatically absorb provisions of large federal bills without new state legislation [3] [4].
2. Concrete examples the sources supply (and why examples matter)
The sources name specific rolling-conformity states as examples—Colorado, Montana, Iowa, Oregon and the District of Columbia are cited as rolling-conformity jurisdictions that faced immediate revenue implications when federal law changed—while Georgia is used as an example of a static state that would not be affected until its conformity date or new legislation updated its laws [6] [7]. Other named nuances include Alabama conforming on a rolling basis despite having its own income starting point and Massachusetts conforming to a fixed year, and Michigan offering taxpayers a choice in conformity reference in certain contexts, which shows the heterogeneity behind the headline counts [5] [1].
3. Why totals and examples diverge in coverage and what that implies
Different publications sometimes report 18 rolling vs 19 static, or 20 vs 18, because states change statutes, suspend conformity for budgetary reasons, or adopt hybrid rules (e.g., Maryland’s temporary suspensions for provisions with revenue impacts, Virginia’s 2023 change with later carve-outs) and because some analyses date their snapshot differently—before or after late-2024/2025 legislative activity—so the aggregate numbers shift [1] [5] [6]. This fluidity is not a reporting error so much as a reflection of real legal movement: rolling conformity can be suspended or partially decoupled; static states can pass annual updates that mimic rolling outcomes; and some states use selective conformity that resists simple categorization [4] [8].
4. Bottom line and how to get an authoritative state-by-state list
Based on the provided reporting, the correct, defensible answer is that most authoritative summaries in 2024–2025 placed 18 states plus DC on rolling conformity and a similar number (18–19) on static conformity for individual income tax, with four states using selective or partial conformity—yet a definitive, current state-by-state roster for 2026 is not contained within these sources and requires consulting the Tax Foundation’s detailed table or each state’s tax code and recent legislation for confirmation [1] [2] [5]. Policymakers, taxpayers and advisers tracking the 2026 implications of large federal legislation should therefore verify each state’s conformity method directly from state revenue department guidance or a current Tax Foundation/Tax Notes state table, because statutory changes, suspensions, and decouplings have been common and materially alter whether federal changes automatically flow to state law [6] [3].