When is the best age to start Roth conversions?

When a conversion makes sense, the usual window is between retirement and RMD age (typically 60 to 73, or 75 if you were born in 1960 or later). In that gap ordinary income is often lower and RMDs haven't started yet, so there is more room in the lower brackets. Once RMDs kick in, your bracket is already partially filled before you convert a single dollar.

How much should I convert per year?

It depends on (1) the top of your target bracket, (2) the IRMAA tier you want to stay under, and (3) how much outside money you have to pay the tax. A typical 'bracket-fill to 22% top' ladder converts $100K to $300K per year for high-balance retirees. Our calculator runs the exact math for your numbers.

Can a Roth conversion push me into a higher tax bracket?

Yes. That can still be worth it in some cases. If your current bracket is lower than the bracket your RMDs will force you into starting at age 73, or 75 if you were born in 1960 or later (or that your surviving spouse will face at single rates), paying 24% now beats paying 32%+ later. The calculator shows your bracket trajectory year by year.

Does a Roth conversion affect my Medicare premiums?

Yes, Roth conversions count as MAGI for IRMAA purposes, with a 2-year lookback. A conversion in 2026 affects your 2028 Medicare Part B and D premiums. The calculator models this lag and includes IRMAA in the lifetime tax cost.

Is there a deadline to do a Roth conversion?

Roth conversions must be completed by December 31 of the tax year. They cannot be done retroactively in April like an IRA contribution. The 5-year rule on each conversion's earnings also starts January 1 of that year.

Does converting to a Roth always beat doing nothing?

No. It depends on the tax rate you pay to convert compared with the rate you or your heirs would pay later, and on how long the money grows. Money you leave alone is not lost: required withdrawals can be reinvested in a taxable account. On this page's default inputs (married couple, both 65, $1.5 million traditional IRA, $400,000 of outside savings, 6% growth, 2026 tax rules, heirs at 22%), the default plan converts about $1.75 million from age 65 through 72 and leaves the family about $31,700 more at age 92 than doing nothing, a difference of under 1% on about $8.1 million. Filling only the 12% bracket comes out about $417,000 ahead, and filling the 24% bracket comes out about $669,000 behind. Run your own numbers, because the answer can go either way.

Roth Conversion Calculator: Convert or Leave It Alone?

Step 1

You and your accounts today

A few numbers to seed the simulation. The defaults reflect a typical Southern California household. Change them to yours.

Filing Status

Your Age

Life Expectancy (plan-to age) On average a 65-year-old man lives to about 83 and a woman to about 86 (SSA 2023 period life table). About half live longer, so plan past the average.

State

Traditional IRA / 401(k) Balance

Existing Roth Balance

Outside (Taxable) Savings, used to pay tax If this runs out, tax is paid from the IRA itself (less efficient). Required withdrawals you do not need for tax are added here and stay invested.

Expected Investment Return (annual)

Inflation / COLA (annual)

Step 2

2026 Medicare Part B rises from $202.90 to $284.10 a month above $109,000 single income, up to $689.90 — 2026 Medicare Part B premium by income tier (IRMAA). Source: CMS 2026 Medicare Part B premium and IRMAA fact sheet. Data: as of January 1, 2026 (premium year 2026, based on 2024 income); checked October 18, 2026.

Your income picture through retirement

All amounts in today's dollars. The simulator inflates them automatically each year.

Other Ordinary Income (pension, wages, rental)

Pension/Wages Stop at Age After this age, only Social Security + RMDs + portfolio.

Interest, Dividends, Capital Gains (annual) Taxable income your outside savings throw off today. The simulator keeps the same share of the balance each year.

Your Social Security at FRA (annual) Annual benefit at your full retirement age (~67).

Spouse's Social Security at FRA (annual)

SS Claiming Age

Step 3

Your conversion strategy

The optimizer compares doing nothing against a multi-year conversion ladder using your chosen ceiling.

Conversion Strategy

Custom Conversion / Year (if custom)

Convert From Age

Convert Through Age Default: stop before RMDs begin (age 73 if born 1951 to 1959, age 75 if born 1960+).

Heir's Marginal Tax Rate (for estate value) Traditional IRA passed at death is taxed at the heir's bracket on withdrawal. Roth is tax-free.

Want this walked through with you?

This tool runs the math. Hans walks through how the publicly available IRS bracket, RMD, and Medicare IRMAA rules apply to your specific numbers. Pure math education, not financial advice. No products sold.

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Hans Goldstein, EA

Founder & Executive Director · Retirement Literacy Foundation, a 501(c)(3) non-profit
Admitted to practice before the IRS

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Key numbers: $202.90 standard Part B premium per month, 2026; $284.10 first IRMAA tier, above $109,000 single / $218,000. — Key numbers: 2026 Medicare Part B premium by income tier (IRMAA). Source: CMS 2026 Medicare Part B premium and IRMAA fact sheet. Data: as of January 1, 2026 (premium year 2026, based on 2024 income); checked October 18, 2026.

Hans Goldstein is an Enrolled Agent, admitted to practice before the Internal Revenue Service. Not affiliated with or endorsed by the IRS.

Roth Conversion Calculator:
Convert, or Leave It Alone?

You and your accounts today

Your income picture through retirement

Your conversion strategy

Want a clean PDF + a walkthrough?

Want this emailed to you?

What Happens Next

Want this walked through with you?

Hans Goldstein, EA

Free live workshop: Social Security & Taxes

Roth Conversion Calculator:Convert, or Leave It Alone?

You and your accounts today

Your income picture through retirement

Your conversion strategy

Want a clean PDF + a walkthrough?

Want this emailed to you?

What Happens Next

Want this walked through with you?

Hans Goldstein, EA

Free live workshop: Social Security & Taxes

Roth Conversion Calculator:
Convert, or Leave It Alone?