SSA-1099 box 5 explained.

The four boxes people look at

The Social Security Administration sends Form SSA-1099 early in the year after the benefits were paid. Pub. 915 explains each box.

Box 3: benefits paid

Box 3 is the total benefits paid in the year to the person named on the form. An asterisk after it means it includes benefits for one or more earlier years, and the form shows how much. Box 3 is built from what you got by check or direct deposit, plus additions, minus subtractions. The additions include the Medicare premiums deducted from your benefits, any voluntary federal tax withheld, amounts withheld for child support or alimony, attorney fees withheld and Treasury offsets. Pub. 915 says do not reduce box 5 by any of those items.

Box 4: benefits repaid to SSA

Box 4 is the total you repaid in the year, including returned checks, amounts withheld because of work or to recover an overpayment, and direct repayments. It can include repayment of benefits that were paid in an earlier year.

Box 5: net benefits

Box 5 is box 3 minus box 4. This is the figure for line 6a of Form 1040, and the starting point for the worksheet that decides how much is taxable. If box 5 is in parentheses, you repaid more than you received. Pub. 915 says that when total repayments exceed gross benefits (box 4 more than box 3), none of your benefits are taxable for the year and you follow its section on repayments larger than gross benefits.

Box 6: voluntary federal income tax withheld

If you asked SSA to withhold federal tax, box 6 shows it. Include that amount as withholding on your return.

Are my benefits taxable?

Not necessarily. Whether any of the benefits are taxable depends on your other income. Pub. 915 gives a quick check: take half of box 5, add your other taxable income and tax-exempt interest, and compare the total with your base amount. At or below it, none of your benefits are taxable. Above it, some may be, and you complete the full worksheet.

• Base amount $25,000: single, head of household, qualifying surviving spouse, or married filing separately and living apart from your spouse all year.
• Base amount $32,000: married filing jointly.
• Base amount $0: married filing separately and lived with your spouse at any time during the year.

Generally up to 50% of benefits are taxable. Up to 85% can be taxable if one half of your benefits plus all other income is more than $34,000 ($44,000 if married filing jointly), or if you are married filing separately and lived with your spouse at any time in the year. The base amounts are the figures printed in the 2025 edition of Pub. 915.

Worked example

Pub. 915’s own example has a single filer with $5,980 in box 5, a $18,600 pension, $9,400 of wages and $990 of interest. Half of box 5 is $2,990, so the quick test is $2,990 plus $28,990, or $31,980, above the $25,000 base. The full worksheet gives taxable benefits of $2,990, entered on line 6b. A second example in the publication has a married couple with $5,600 in box 5 and $29,750 of other income: $2,800 plus $29,750 is $32,550, which is above $32,000 but the full worksheet, which subtracts adjustments such as a deductible IRA contribution, finds none of the benefits taxable.

Where to get a copy

The IRS notes that SSA-1099 and SSA-1042S can be obtained online from the Social Security Administration, avoiding mail delays. IRS Tax Topic 423 also says you should receive the form by early February. Railroad Retirement Board recipients get Form RRB-1099 instead, where box 5 is the net Social Security equivalent benefit portion of Tier 1, so make sure you are reading the right form.

Sources

• Publication 915 (2025) — box 3, 4, 5 and 6 definitions; Worksheet A; base amounts; 50% and 85%
• IRS Tax Topic 423 — getting the form online; who is taxed; reporting

Figures and rules above were retrieved November 2026 from the IRS pages listed. The base amounts and worksheet are from the 2025 edition of Publication 915, the latest read; confirm against the 2026 edition when it is published.

Frequently asked questions

What is box 5 on the SSA-1099?

Box 5 is net benefits: box 3 (benefits paid) minus box 4 (benefits repaid). It goes on line 6a of Form 1040 and is the starting figure for working out how much is taxable.

Why is box 3 higher than the money I received?

Box 3 includes amounts SSA took out before paying you, such as Medicare premiums, voluntary tax withholding, child support or alimony withholding and attorney fees. Pub. 915 says not to reduce box 5 by those items.

Is my Social Security taxable?

Only if half of your benefits plus your other income and tax-exempt interest is above the base amount for your filing status: $25,000 single, $32,000 married filing jointly. Up to 50% is taxable at that level, and up to 85% above $34,000 ($44,000 joint).

What does a negative box 5 mean?

You repaid more than you received. Pub. 915 says that when repayments are more than gross benefits, none of your benefits are taxable for the year.

Are Medicare premiums deductible against box 5?

Not by reducing box 5. The premiums are part of box 3 and stay in box 5. Any medical expense deduction for them is a separate matter on Schedule A.