IRA Pro-Rata Rule
Category: Retirement & health · Related form: Form 8606
When you convert or distribute from traditional IRAs that include nondeductible basis, the taxable portion is generally prorated across all non-Roth IRA balances.
How IRA Pro-Rata Rule fits 2026 planning
IRA Pro-Rata Rule sits inside retirement contribution limits, distribution timing, and how pre-tax vs Roth choices change AGI. For tax year 2026, US Tax Tools treats year-scoped constants (brackets, contribution limits, wage bases, credit schedules) as separate datasets — so explanations of IRA Pro-Rata Rule should be read with the same year selected in any linked calculator.
Category focus: Retirement & health. Readers usually land on this page while comparing a paycheck estimate, a credit phaseout, or a retirement contribution room figure that depends on understanding IRA Pro-Rata Rule first.
Worked example
If 10% of your combined traditional IRA balance is after-tax basis, roughly 10% of a conversion is nontaxable.
Treat the example as a teaching sketch, not a filing position. Change filing status, state residency, or mid-year events and the same definition of IRA Pro-Rata Rule can produce a different cash outcome even when the glossary text stays the same.
What to watch for
Definitions of IRA Pro-Rata Rule can differ slightly across IRS publications, SSA rules, Marketplace subsidy worksheets, and state agencies. When two programs both say “income,” confirm which modification rules apply — MAGI for one credit is not always MAGI for another.
Legislation and inflation adjustments can move the dollar thresholds around IRA Pro-Rata Rule without renaming the concept. Prefer the effective date on the primary source (Rev. Proc., SSA notice, USDA table, or state DOR bulletin) over any blog summary — including this one if a later notice supersedes it.
On a filed return, IRA Pro-Rata Rule most often surfaces around Form 8606. Read the official IRS instructions for that form for the tax year you are filing — glossary pages summarize concepts; they do not replace line-by-line worksheets.
Next step
When you are ready to model numbers, open the IRA Pro-Rata Rule related calculator on US Tax Tools. Engines keep tax-year datasets separate so a 2025 habit does not silently reuse a 2026 constant.
Related reading: Tax insights for longer 2026 explainers, Methodology for how engines store cents and traces, and Disclaimer for educational-use limits.