Claiming Rules
Understanding Combined Income and the 85% Taxability Threshold for Social Security
Verified against SSA POMS as of September 8, 2026
The short answer
Combined income, also commonly referred to as provisional income, is used to determine whether Social Security benefits are subject to federal income tax. It includes adjusted gross income, tax-exempt interest, and one-half of Social Security benefits.
Depending on filing status and combined income, up to 50% or up to 85% of Social Security benefits may be included in taxable income. An 85% inclusion does not mean the benefits are taxed at an 85% tax rate.
What is Combined Income?
Combined income is calculated by adding:
- Adjusted Gross Income, before including taxable Social Security benefits;
- Tax-exempt interest, such as interest from certain municipal bonds; and
- One-half of Social Security benefits received during the year.
Certain adjustments may be required when calculating the income used to determine Social Security taxation. IRS Publication 915 provides the worksheet used to make the complete calculation.
GN 05001.016IRS Publication 915Social Security Taxability Thresholds
The thresholds depend on filing status:
| Filing Status | Up to 50% Taxable | Up to 85% Taxable |
|---|---|---|
| Single, Head of Household, Qualifying Surviving Spouse | $25,000–$34,000 | Over $34,000 |
| Married Filing Jointly | $32,000–$44,000 | Over $44,000 |
| Married Filing Separately and lived apart from spouse for the entire year | $25,000–$34,000 | Over $34,000 |
For married filing separately taxpayers who lived with their spouse at any time during the year, the rules are substantially less favorable: the base amount is $0.
These thresholds are not indexed for inflation.
GN 05001.016IRS Publication 915IRC §86Calculating the Taxable Portion of Social Security
The amount of Social Security included in taxable income depends on combined income and filing status.
When combined income exceeds the first threshold, up to 50% of Social Security benefits may become taxable. Once combined income exceeds the second threshold, the calculation can result in up to 85% of Social Security benefits being taxable.
Crossing the second threshold does not automatically make 85% of the entire Social Security benefit taxable. The actual taxable amount is determined using the IRS calculation and cannot exceed 85% of benefits.
For example, receiving $30,000 of Social Security does not mean someone in the 85% range owes $25,500 in tax. It means no more than $25,500 can be included in taxable income, and that amount is then subject to the individual's applicable federal income tax rates.
IRS Publication 915IRC §86Frequently asked
Does 85% taxability mean I pay an 85% tax rate on my Social Security benefits?
No. It means that up to 85% of your Social Security benefits can be included in taxable income. The taxable portion is then subject to your applicable federal income tax rates.
Are the Social Security taxability thresholds adjusted for inflation?
No. The income thresholds used to determine the federal taxation of Social Security benefits are not indexed for inflation.
Do tax-exempt municipal bond interest payments count toward Social Security taxability?
Yes. Tax-exempt interest is included in combined income when determining whether Social Security benefits are taxable, even though the interest itself may be exempt from federal income tax.
Can IRA withdrawals cause more of my Social Security benefits to become taxable?
Yes. Taxable traditional IRA distributions increase AGI and therefore can increase combined income. This can cause a greater portion of Social Security benefits to be included in taxable income.
Will a Roth IRA distribution increase my combined income and cause more of my Social Security benefits to be taxable?
A qualified Roth IRA distribution will not. Qualified Roth IRA distributions are not included in gross income and therefore do not increase combined income used to determine the taxable portion of Social Security benefits. However, if a Roth IRA distribution is not qualified and a portion of the distribution is taxable, the taxable portion included in income can affect the combined income calculation.