Retirement Tax Calculator
See your actual tax burden from different retirement income sources — including how much of your Social Security is taxable, bracket room for Roth conversions, and IRMAA Medicare thresholds.
Income Breakdown
Bracket Room Analysis
How Social Security Taxation Works
Unlike most income, Social Security isn't taxed on its face value. The IRS uses a "combined income" formula: AGI + nontaxable interest + ½ × SS benefit. Based on this combined income, 0%, 50%, or 85% of your SS benefit is added to taxable income.
- Single: Combined income under $25,000 → 0% taxable. $25,000–$34,000 → up to 50%. Over $34,000 → up to 85%.
- Married filing jointly: Under $32,000 → 0%. $32,000–$44,000 → up to 50%. Over $44,000 → up to 85%.
Important: "up to 85%" doesn't mean 85% of SS is taxed at 85%. It means a maximum of 85% of your SS benefit is included in your taxable income — then normal income tax rates apply to that portion.
IRMAA Thresholds (2026)
Medicare Part B premiums rise with income via IRMAA surcharges. The income used is your MAGI from 2 years prior. Surcharges are per person per month:
| MAGI (Single) | MAGI (MFJ) | Extra Premium/mo |
|---|---|---|
| ≤$106,000 | ≤$212,000 | $0 |
| $106,001–$133,000 | $212,001–$266,000 | +$74/mo |
| $133,001–$167,000 | $266,001–$334,000 | +$185/mo |
| $167,001–$200,000 | $334,001–$400,000 | +$296/mo |
| Over $200,000 | Over $400,000 | +$407–$444/mo |
Frequently Asked Questions
How much of Social Security is taxable?
It depends on combined income (AGI + nontaxable interest + ½ SS). Under $25,000 single / $32,000 MFJ: 0% taxable. $25,000–$34,000 single / $32,000–$44,000 MFJ: up to 50%. Above those: up to 85%.
What is a Roth conversion and why do it in retirement?
A Roth conversion moves pre-tax money to Roth — you pay tax now, get tax-free withdrawals later. Best done in the "gap years" between retirement and RMD onset (ages 60–72) when income is lower. Reduces future mandatory taxable RMDs.
What is IRMAA and when does it apply?
IRMAA is a Medicare Part B and D premium surcharge for higher-income retirees. Applies when MAGI exceeds $106,000 (single) / $212,000 (MFJ) in 2026. The surcharge is per person per month — it can cost married couples $1,788/year or more in extra premiums.
What is the best bracket to fill with Roth conversions?
Fill the current bracket without pushing into the next. Most retirees in the pre-RMD gap years have lower-than-working income, making the 12% or 22% bracket ideal to fill with conversions before RMDs force higher withdrawals.
Do RMDs change my tax bracket?
Yes. RMDs (starting at age 73) are fully taxable as ordinary income. Large pre-tax balances generate mandatory taxable withdrawals that can push you into higher brackets and make more SS taxable. Pre-RMD Roth conversions reduce this future tax drag.
Are state taxes included?
This calculator shows federal taxes only. Many states fully or partially exempt retirement income and Social Security. Check your state's rules and add the estimated state tax for a complete picture.