Tax on Social Security benefits: how much of your check is taxable

Is Social Security taxable?

Social Security is taxable for some people and not others. The tax on Social Security benefits depends on a test the IRS calls modified adjusted gross income plus half of your benefits, and the Social Security Administration calls combined income. If that total stays at or under your base amount, none of your benefits are taxable income.

Retirement, survivor and disability benefits are all treated the same way, along with the Social Security equivalent part of tier 1 railroad retirement benefits. Supplemental Security Income (SSI) is not taxable. The amount you received appears in box 5 of Form SSA-1099, which SSA mails each January.

What is combined income for Social Security?

Combined income is your adjusted gross income from all other sources, plus tax-exempt interest, plus half of your net Social Security benefits. It is not the same as AGI: municipal bond interest that is otherwise tax free is added back in, and so are a few excluded items such as foreign earned income and employer adoption benefits (Publication 915).

Pension payments, wages, interest, dividends, capital gains and traditional IRA or 401(k) withdrawals all count. That is why a single large retirement account withdrawal can make benefits taxable in a year when they normally are not; our page on tax on a 401(k) withdrawal shows how that payout itself is taxed.

Base amounts: when does Social Security become taxable income?

Social Security becomes taxable income once combined income passes the base amount for your filing status. A second, higher threshold marks where the 85% tier begins. These dollar amounts are set in the tax code and are not indexed for inflation, so they apply to 2026 returns exactly as they did to 2025 returns. Benefits, by contrast, rise with the cost-of-living adjustment (COLA), which is 3.6% for 2027, so over time more retirees cross the fixed thresholds.

How much of my Social Security is taxable: 50% or 85%?

The taxable share is figured in two tiers, and the percentage is a ceiling, not a flat rate. Between the base amount and the second threshold, the taxable amount is the smaller of half your benefits or half of the income above the base amount. Above the second threshold, 85% of the extra income is added, plus a capped amount from the first tier, and the total can never exceed 85% of benefits.

1. Add half of your benefits to your other income and tax-exempt interest.
2. Subtract the base amount ($25,000 or $32,000). If the result is zero or less, stop: no benefits are taxable.
3. If you are below the second threshold, taxable benefits equal the smaller of half the excess or half your benefits.
4. If you are above it, take 85% of the income over $34,000 or $44,000 and add the smaller of half your benefits, $4,500 (single) or $6,000 (joint).
5. Compare that total with 85% of your benefits. The smaller figure goes on Form 1040 line 6b; total benefits go on line 6a.

Publication 915 Worksheet 1 performs these steps line by line, and tax software does the same. Both tiers describe how much of the benefit is added to income; the tax itself then depends on your bracket.

Worked example: how much federal tax on my Social Security?

Take a single filer aged 67 in 2026 with $24,000 of Social Security, a $30,000 pension and $1,000 of bank interest. Combined income is $31,000 of other income plus $12,000 (half the benefits), or $43,000, which is above the $34,000 second threshold.

Her AGI is $31,000 plus $12,150, or $43,150. She subtracts the $16,100 single standard deduction, the $2,050 additional amount for age 65, and the $6,000 senior deduction (her modified AGI is under $75,000), leaving taxable income of $19,000. Federal tax is $1,240 on the first $12,400 plus 12% of $6,600, or $2,032. Without any benefits being taxable she would have owed $685, so about $1,347 of her bill is the tax on Social Security.

Does the senior deduction make Social Security tax free?

No. The $6,000 senior deduction, available for tax years 2025 through 2028 to people 65 or older, does not change how much of your Social Security is taxable. It is subtracted after AGI, so it lowers taxable income and the tax you pay, but line 6b is calculated exactly as before.

For many retirees the practical result is still zero tax. A married couple, both 66, with $40,000 of combined benefits and $20,000 of IRA withdrawals has combined income of $40,000, so $4,000 of benefits is taxable and AGI is $24,000. Their 2026 deductions of $32,200 standard, $3,300 for age and $12,000 senior total $47,500, so taxable income is zero. The rules and income phaseout are on our senior deduction page, and the age add-on is covered in standard deduction over 65.

How to have tax withheld from Social Security

If part of your benefits will be taxable, you can ask SSA to withhold federal income tax by giving Form W-4V, Voluntary Withholding Request, to the payer, which for these benefits is SSA (the form itself says not to send it to the IRS). The January 2026 revision lets you choose 7%, 10%, 12% or 22% of each payment; no other percentages are allowed.

The alternative is quarterly estimated tax on Form 1040-ES, generally required if you expect to owe at least $1,000 after withholding. Many retirees find W-4V simpler, and you can combine it with withholding from a pension or IRA on Form W-4P or W-4R.

Special cases: lump-sum back payments and children's benefits

If a lump-sum payment includes benefits for earlier years, you can elect to figure the taxable part as if each prior year's benefits had been received in that year, which often lowers the amount. Publication 915 has separate worksheets for this, and you check the box on Form 1040 line 6c. You do not amend the earlier returns.

Benefits paid to a child, such as survivor benefits, are the child's income, not the parent's, even if deposited to the parent's account. The same combined income test applies to the child, and the taxable part is unearned income that can fall under the kiddie tax rules. For how benefits fit into the full income calculation, see how taxable income is calculated.