Taxes
Social Security Tax Calculator
Up to 85% of a Social Security benefit can be subject to income tax. What decides it is provisional income — your other income, plus tax-exempt interest, plus half the benefit — measured against thresholds Congress set in 1984 and never indexed to inflation.
Pensions, IRA withdrawals, wages, dividends, capital gains.
Municipal bond interest counts here even though it is not taxed itself.
Taxable portion of your benefit
$5,350
17.8% of the benefit falls into the 85% tier.
These thresholds were set in 1984 and have never been adjusted for inflation. What once affected roughly one in ten recipients now affects the majority, and will keep spreading.
- Provisional income
- $35,000
- Tax on the benefit
- $642
- Benefit you keep
- $29,358
Other income + tax-exempt interest + half the benefit.
How this calculator works
Provisional income is other income plus tax-exempt interest plus half the benefit. Below the first threshold nothing is taxable. Between the thresholds, the taxable amount is the lesser of half the excess over the first threshold or half the benefit. Above the second threshold it is 85% of the excess plus the first-tier carry, capped at 85% of the benefit. This follows the IRS Publication 915 worksheet.
Thresholds are the statutory $25,000/$34,000 for single filers and $32,000/$44,000 for joint. Married filing separately while living with a spouse uses $0 and is not offered here. A flat marginal rate is applied to the taxable portion; real filing runs it through brackets. State tax is not modelled.
Try an example
Frequently asked questions
How much of my Social Security is taxable?
Nothing below the first threshold. Between the thresholds, up to 50% becomes taxable. Above the second, up to 85%. It is never more than 85% — the remaining 15% is always free of federal income tax, no matter how high your income.
What is provisional income?
Also called combined income: your adjusted gross income, plus tax-exempt interest, plus half your Social Security benefit. It exists only for this calculation and appears nowhere else on your return, which is why it catches people out.
Why do the thresholds never change?
They were written into law in 1983 and 1993 without inflation indexing. $25,000 in 1984 is worth roughly $80,000 today. What was designed to tax the benefits of higher earners now reaches most recipients, and will reach more each year by design of the omission.
Do municipal bonds help?
Not for this. Tax-exempt interest is added back into provisional income in full. Muni bonds avoid tax on the interest itself but can push more of your Social Security into the taxable range, sometimes leaving you worse off than a taxable bond would have.
How can I reduce the tax on my benefit?
Manage the timing of other income. Roth conversions before claiming, Roth withdrawals after — which do not count toward provisional income — and qualified charitable distributions from an IRA all help. So does drawing from taxable accounts in the years before benefits start.
Do states tax Social Security?
Most do not. A shrinking handful still tax some portion, and several have phased it out in recent years. Check your state's current rules — this calculator covers federal tax only.
Related calculators
Social Security Break-Even Calculator
Claim early for smaller cheques sooner, or wait for larger ones later? Find the age at which waiting overtakes claiming early, using your own benefit estimates.
RMD Calculator
Calculate your required minimum distribution from a traditional IRA or 401(k) using the IRS Uniform Lifetime Table, with the tax due and a projection of future years.
Retirement Calculator
Project your retirement savings: what your balance could reach by retirement age and the monthly income it could sustainably provide.
Federal Income Tax Calculator
Estimate your 2026 federal income tax: total tax, effective and marginal rates, and a bracket-by-bracket breakdown using official IRS figures.
Disclaimer: DayCents provides this calculator for educational purposes only. Results are estimates based on your inputs and the stated assumptions — they are not financial advice, a quote, or an offer of credit. Consult a qualified financial professional before making major money decisions.