How are Required Minimum Distributions taxed?

RMDs from traditional 401(k)s and IRAs are taxed as ordinary income in the year you take them. They stack on top of Social Security and other income, potentially pushing you into higher federal brackets and triggering Medicare IRMAA surcharges.

What age do RMDs start?

Under SECURE 2.0, the RMD starting age depends on birth year. Born 1950 or earlier: age 72. Born 1951–1959: age 73. Born 1960 or later: age 75.

What is the IRMAA surcharge and how do RMDs trigger it?

IRMAA is an income-based Medicare Part B and Part D surcharge. In 2026, single filers with MAGI above $109,000 pay an extra $1,164/year; above $137,000, the surcharge rises to $2,885/year. Because RMDs increase your MAGI, they can push you across these thresholds and add thousands in annual Medicare costs.

How does Social Security become 85% taxable?

When provisional income (your adjusted gross income plus half your Social Security benefit) exceeds $34,000 for single filers or $44,000 for married filers, up to 85% of your Social Security benefit becomes taxable. RMDs directly increase provisional income, which often causes this cascade.

Can Roth conversions reduce RMD taxes?

Yes. Moving money from a traditional IRA or 401(k) to a Roth account before RMDs begin reduces the taxable balance subject to RMDs. Roth accounts have no RMD requirement, so converted funds grow and are withdrawn tax-free in retirement.

What is a QCD and how does it reduce RMD taxes?

A Qualified Charitable Distribution (QCD) lets you transfer up to $108,000/year (2026 limit) directly from your IRA to a qualified charity. QCDs satisfy your RMD requirement but are excluded from taxable income entirely—keeping them out of MAGI and below IRMAA thresholds.

RMD Tax Calculator: Required Minimum Distribution Pressure by Age

Model the IRS Uniform Lifetime Table divisor across your 70s, 80s, and 90s. See where RMD pressure pushes you into the next bracket — and how pre-RMD Roth conversions can defuse it.

Jump to calculator Full Praxion plan (free) — model RMD pressure with Roth conversion windows →

IRS Uniform Lifetime Table + 2026 brackets. Pre-tax; full IRMAA cascade in the in-product plan.

RMD as % of balance · by age

Source: IRS Uniform Lifetime Table. Numbers shown are RMD as % of prior-year-end balance.

Your Numbers

Current Age

RMD age: 75 · 20 years away

Pre-Tax Balance (IRA / 401k)

Today's balance, grown to age 75 at 6.0% → $2.4M

Filing Status

Monthly Social Security Benefit

$24,000/year · up to 85% taxable when RMDs begin

Investment Growth Rate — 6.0%

3%9%

Annual Roth Conversion (pre-RMD)

Used in the "With Conversions" scenario below

Estimated Cumulative RMD Tax Burden

$1.4M

Federal income tax + Medicare IRMAA surcharges · ages 75–90 · 46 years

First RMD (Age 75)

$98K

÷ 24.6 (IRS factor)

Year-1 Tax on RMD

$18K

Fed $17,169 + IRMAA $1,164

Cumulative Federal Tax

$1.2M

On $6.0M in total RMDs

Peak Marginal Rate

32.0%

~59.2% effective w/ SS cascade

⚠

Social Security Taxation Cascade Detected. RMDs push provisional income above $34K, making 85% of your SS benefit taxable. Your effective marginal rate on each RMD dollar reaches 59.2% (bracket × 1.85).

⚠

IRMAA Medicare Surcharge Triggered. Starting at age 75, RMDs push MAGI above the $109K threshold, adding $1,164/year in Medicare Part B + D surcharges ($148K cumulative). IRMAA uses a 2-year MAGI lookback—plan early.

Year-by-Year RMD Schedule

Expand ▼

Without Conversions

$1.4M

$1,208,307 federal tax + $148,489 IRMAA
over 46 years of RMDs starting at age 75

With $30,000/yr Roth Conversions

$511K

$375K moved to Roth over 20 years
before RMDs begin — smaller taxable balance, smaller RMDs

Save $846K in RMD taxes

Why RMDs Spike Your Tax Rate

RMDs are fully ordinary income—stacked on top of Social Security and any other income. Because the tax code is progressive but RMD amounts grow with your balance each year, the incremental cost compounds decade over decade. A $750K balance at age 55 can produce over $2M in lifetime RMDs by age 90.

The IRMAA Medicare Cliff

Medicare Part B and D premiums jump in discrete tiers based on your MAGI from two years prior. A single dollar over the $109K threshold adds $1,164/year in surcharges. RMDs that push you across this line create a hidden tax that doesn't appear in your federal bracket.

The Social Security Cascade

Once provisional income exceeds $34,000 (single), 85% of your SS benefit becomes taxable. This creates an effective marginal rate of bracket × 1.85—so a 22% bracket actually costs you 40.7 cents per dollar of additional RMD income. QCDs and Roth conversions reduce this exposure dollar-for-dollar.

Get a Personalized RMD Tax Strategy

This calculator estimates your broad exposure. Praxion Finance builds a year-by-year plan tied to your actual balances, Social Security age, Roth conversion capacity, QCD opportunity, and bracket targets—so you can act before RMDs begin.

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Disclosure: This calculator uses 2026 IRS Uniform Lifetime Table divisors, federal tax brackets, standard deductions, and Medicare IRMAA thresholds. It applies a simplified model: RMDs and Social Security are the only income sources; IRMAA uses same-year MAGI rather than the IRS two-year lookback; state taxes are excluded. Results are estimates for educational purposes only and do not constitute tax or financial advice. Consult a qualified tax professional for personalized guidance.