Planning workspace · reviewed October 10, 2026

December 31 IRA balance simulator

Test how changes in projected year-end IRA assets affect the modeled result. The simulator cannot predict investment performance or guarantee transfer completion.

2025 standard rules · 2026 form projections

See how an applicable December 31 IRA balance changes the allocation. The numeric input and slider control the same traditional IRA amount. SEP and SIMPLE amounts are added separately.

Tax yearPlanned Roth conversion ($)Traditional IRA year-end balance ($)SEP IRA year-end balance ($)SIMPLE IRA year-end balance ($)Prior nondeductible basis ($)Current-year nondeductible contribution ($)Contribution made after year-end ($)Other eligible IRA distributions ($)Outstanding rollover adjustment ($)Federal tax estimate modeAssumed marginal federal rate (decimal)0.24 means 24%. State taxes excluded.

December 31 traditional IRA balance slider

2026 Form 8606 projection uses the finalized 2025 structure; final 2026 instructions were not verified.

Year-end allocation

Nontaxable ratio25.00%

Tax-free conversion$1,750.00

Taxable conversion$5,250.00

Remaining basis$5,250.00

Basis ÷ (applicable year-end value + eligible distributions + conversion) gives the allocation ratio. Timing is measured for the calendar year of the conversion.

Reviewed October 10, 2026. IRS reference. 2026 Form 8606 output is a planning estimate based on the 2025 structure.

Compare projected balances

Use your best supported year-end estimate, then test a later incoming rollover and a confirmed eligible outgoing transfer. Keep the annual conversion total fixed so the effect is clear.

Close the loop

Replace projections with actual year-end statements before filing. Identify outstanding transfers explicitly and check their treatment against the relevant instructions.

Sources and next steps

Reviewed October 10, 2026. This independent educational website is not affiliated with the IRS. Special transactions need professional review.

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