How it works
Social Security uses a 'combined income' test: your other income plus half your Social Security benefit. Below the first threshold, none of your benefit is taxed. Between the two thresholds, up to 50% is taxable. Above the second threshold, up to 85% is taxable. This calculator applies the IRS formula directly.
Who this is for
Anyone collecting Social Security who also has other income — a pension, part-time work, or investment income — and wants to know how much of their benefit the IRS will actually tax this year.
Worked example
A single filer with a $24,000 annual Social Security benefit and $30,000 of other income has a combined income of $42,000 ($30,000 + half of $24,000). That's above the $34,000 upper threshold for single filers, so up to 85% of the benefit can be taxable — in this case, about $20,400 of the $24,000 benefit.
Frequently asked questions
Can 100% of my benefit ever be taxed? No — the maximum taxable share is 85%, no matter how high your other income is.
What counts as 'other income'? Wages, pension and 401(k)/IRA withdrawals, interest, dividends, and even tax-exempt municipal bond interest all count toward combined income.
Do the thresholds change over time? The $25,000/$32,000 and $34,000/$44,000 thresholds are not indexed for inflation and have stayed fixed for decades, which means more retirees owe tax on their benefits every year as incomes rise.
Does this affect my Social Security claiming decision? It can — see the break-even calculator and consider taxation alongside timing.