Use Form SSA-1099 to identify Social Security benefits received, benefits repaid, net benefits, and federal tax withheld. The net benefit figure is not automatically the taxable amount. Determine the taxable portion using the instructions for the return year and your other income. [1]
What do boxes 3, 4, and 5 mean?
| Box | General meaning | How to approach it |
|---|---|---|
| 3 | Benefits paid during the year | Read the accompanying description of payments |
| 4 | Benefits repaid during the year | Keep any repayment records |
| 5 | Net benefits: box 3 less box 4 | Use the applicable tax worksheet to determine taxability |
| 6 | Voluntary federal income tax withheld | Report as withholding under the return instructions |
Publication 915 explains the relationship among the benefit and repayment boxes. For example, $18,000 in box 3 and $1,000 in box 4 produces $17,000 in box 5. That subtraction establishes net benefits, not the final taxable amount. [1]
Read box 6 separately
SSA explains that box 6 shows benefits withheld and paid toward federal income tax. Withholding is a tax payment; it should not be subtracted from box 5 a second time to invent a lower benefit figure. SSA’s instructions also address attaching the statement to a paper federal return when voluntary tax withholding is shown. Follow the filing instructions for your method of submission. [2]
If you want a different amount withheld from later payments, use the Social Security voluntary withholding procedure. Changing the election and correctly reporting last year’s statement are separate tasks.
How much of the benefits is taxable?
The calculation considers benefits, other income, and filing status. Depending on the circumstances, some benefits may be nontaxable, while as much as 85% may be included in taxable income. An 85% inclusion is not an 85% tax rate. Publication 915 provides the worksheets and special rules, including treatment of certain lump-sum payments and repayments. [1]
Use a complete income list before calculating: wages, pensions, interest, dividends, and other relevant income. A bank deposit total alone cannot identify all the information a tax worksheet requests. If spouses file jointly, gather both spouses’ applicable records.
Where does the information go on Form 1040?
For the 2025 Form 1040 or 1040-SR, the instructions use line 6a for Social Security benefits and line 6b for the taxable portion. Federal withholding from Form SSA-1099 is reported in the applicable withholding section, rather than as an additional benefit deduction. Confirm the line labels for any other tax year because forms can change. [3]
Our Form 1040 reference and Publication 915 reference help you locate the relevant official materials.
Check these items before filing
- The form belongs to the person whose benefits you are reporting.
- The tax year matches the return.
- Any corrected statement has been considered.
- Benefits and federal withholding have not been combined into one figure.
- Special lump-sum or repayment facts have been reviewed.
- The calculation uses the correct year’s instructions.
If the form is missing, see how to obtain an SSA-1099. If you are checking whether the return itself was already filed, use IRS filing records, since possession of a benefit statement does not establish a completed tax filing.
Primary sources
- IRS Publication 915: Social Security benefits and worksheets
- SSA POMS GN 05002.016: Box 6 and voluntary withholding
- IRS: Instructions for Form 1040 and 1040-SR
Sources checked: October 31, 2026.