Updated October 17, 2026. Quick answer: Box 6 of Form SSA-1099 shows the total federal income tax withheld from your benefits. Publication 915 says to include that amount on your income tax return as tax withheld. Withholding from social security is voluntary: you ask for it on Form W-4V.
What box 6 reports
The publication describes the box in two sentences: “This shows the total amount of federal income tax withheld from your benefits.” “Include this amount on your income tax return as tax withheld.”
The box is labelled “Box 6. Voluntary Federal Income Tax Withheld” on the statement. The word voluntary matters: unlike a paycheck, social security payments have no tax taken out unless the recipient asks. The other boxes on the same statement are laid out in the SSA-1099 and RRB-1099 boxes guide.
How the withholding gets started
The publication explains the request: “You can choose to have federal income tax withheld from your social security benefits”. It adds the paperwork: “If you choose to do this, you must complete a Form W-4V.” The form is listed in the publication’s list of related forms as “Voluntary Withholding Request”. It is a different form from the Form W-4 used for wages.
The publication names the alternative for people who choose not to withhold: “If you don’t choose to have income tax withheld, you may have to request additional withholding from other income or pay estimated tax during the year.” The mechanics of paying during the year are covered on the estimated taxes page.
Where box 6 goes on the return
The instruction is to include the box 6 amount as tax withheld. That means the amount counts as tax already sent to the IRS for you. On the Form 1040 page you can see where payments and credits are collected.
Box 6 also shows up inside the description of box 3. One of the addition lines reads “Voluntary federal income tax withheld.” and the publication explains: “This shows the total amount of federal income tax withheld from your benefits.” So the same amount is part of the gross figure in SSA-1099 box 3 and is not deducted again from SSA-1099 box 5. The publication’s tip says “Don’t reduce the amount of net social security benefits (box 5) by any of the items listed below.”
Reading box 6 on your own statement
Start with the label and the number. The sample form prints the heading “Box 6. Voluntary Federal Income Tax Withheld” above the amount. The same sample page carries the instruction “DO NOT RETURN THIS FORM TO SSA OR IRS”, so the statement is a record for you to keep and to copy figures from, not a document to send in.
Box 6 also appears as a line inside the box 3 description, which is explained on the page for SSA-1099 box 3. The net figure that feeds the taxable-benefit worksheets is on the page for SSA-1099 box 5. The repayment side is covered on the page for SSA-1099 box 4.
Compare the nonresident form
Nonresident aliens receive a different statement. The publication introduces it with “Forms SSA-1042S and RRB-1042S, for nonresident aliens, contain the same items plus a few additional ones.” On Form SSA-1042S the withholding figure is in a different box: the heading is “Amount of Tax Withheld”, and the publication says “This is the amount of tax taken out of your social security checks.” If your statement is an SSA-1099, box 6 is the box that matters for this page. The railroad equivalent of the SSA-1099 is covered in RRB-1099 box 3.
Related lines and pages
The Medicare premium line has its own page: the Medicare premium line. It is one of the other amounts that may be taken from your payment before you receive it, but it is not tax withholding. The same withholding idea on a different form is explained on the 1099-NEC and 1099-MISC box 4 page. For how the taxable portion of benefits is figured, see the Social Security tax torpedo page.
Edition and box numbers
The primary read for this page is Publication 915 for 2025 returns, the IRS publication that explains Forms SSA-1099 and RRB-1099 and reproduces a sample SSA-1099. It describes the form with the words “Form SSA-1099, Social Security Benefit Statement 2025”. Only that edition was read for this page, so no wording is compared against any other edition. The box is numbered 6 on the SSA-1099 sample form, which labels it “Box 6. Voluntary Federal Income Tax Withheld”. On the nonresident form the withholding amount sits in box 7, so box numbers differ between the two statements. The sample in the publication carries its own caution: “You should, however, compare the form you received with the one shown in this publication to note any differences.” Check the tax year printed on the statement you received before relying on any box description here.
Common mistakes
- Leaving box 6 off the return. The publication says to “Include this amount on your income tax return as tax withheld.”
- Assuming tax was taken out automatically. The publication says “You can choose to have federal income tax withheld from your social security benefits”.
- Using the wrong form to start withholding. The publication says “you must complete a Form W-4V”.
Related: Form W-4, first-year estimated taxes, 1099-NEC and 1099-MISC box 4, and Form 1040.
Sources
- Publication 915, Social Security and Equivalent Railroad Retirement Benefits (for 2025 returns): https://www.irs.gov/pub/irs-pdf/p915.pdf
- IRS web edition of Publication 915 (2025): https://www.irs.gov/publications/p915
Read from the IRS documents linked above on October 17, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.