Most Roth calculators ask one year. The real money is in the window.

Between retirement and the year RMDs start, most retirees sit in a tax-bracket valley nobody told them about — a window where converting some traditional IRA to Roth costs almost nothing and saves a fortune later. This calculator shows the window.

Current Age 62

Traditional IRA Balance $1,000,000

Other Annual Income (post-retirement) $40,000

Filing Status: MFJ

Expected Future Tax Bracket — federal 24%

Annual Conversion Target
$58,000
to fill 12% bracket each year

Total Window Capacity

$638,000

across the window years

Lifetime Tax Savings

$76,560

vs converting later at higher bracket

Tax-Free Conversion Room

$0/year

Your other income already fills the standard deduction — no tax-free room, but 10%-bracket conversion is still cheap.

Suggested Year-by-Year Conversion Schedule

Year	Age	Suggested Conversion	Estimated Tax	Bracket Filled

What this calculator deliberately doesn't model

State tax (typically amplifies savings by 2–13%) · IRMAA (Medicare Part B/D surcharges triggered ~$103K single / $206K MFJ MAGI in 2026; a Roth conversion can push you over a bracket and cost $1K–$5K extra) · ACA subsidy impact (critical pre-65 — see the Healthcare Bridge calc; conversions raise MAGI and can wipe out the credit) · Social Security taxation (up to 85% becomes taxable based on provisional income) · NIIT (3.8% on investment income above thresholds). A real Roth conversion strategy stacks these together. This calc gets the bracket math right — the planning conversation gets the rest.

* Calculator uses 2026 federal brackets (single / MFJ) and assumes the goal is to fill the 12% bracket each year. RMD age is computed per SECURE Act 2.0: 75 for those born 1960+ (age ≤66 in 2026); 73 for those born 1951–1959. The federal-bracket framing keeps the math apples-to-apples — state tax amplifies the savings (e.g., 24% federal + 5% state means actual marginal saved is 29%). Does not model state tax, IRMAA Medicare surcharges, ACA subsidy impacts (critical if pre-65), Social Security taxation interaction, or NIIT. A real Roth conversion strategy needs to model all of these. Run this, then talk to a CPA or advisor.

The framework

The "Roth conversion window" is the gift most retirees leave on the table.

For most people who retire before age 73 (the current RMD age), there's a window of 5–15 years where their taxable income drops dramatically — they're no longer earning a paycheck, but they're not yet forced to take Required Minimum Distributions. The temptation is to enjoy the low-tax years. The smarter play is usually the opposite: convert traditional IRA dollars to Roth during this window, at low marginal rates, before RMDs force you back into a higher bracket.

Pay the tax now at 12% — or pay it later at 24%, possibly 32%, after RMDs and Social Security stack.

The math gets sharper once you account for IRMAA (Medicare surcharges that kick in at higher income), the ACA subsidy cliff before age 65, and the way Social Security taxation interacts with provisional income. The window has tradeoffs — but ignoring it usually costs more than running into them.

Roth conversion timing is one of the highest-value planning moves there is. And one of the most under-used.

If you're inside (or approaching) the window, this is a 30-minute conversation worth having.

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