Updated August 14, 2026. Quick answer: box 5 is labelled “net benefits” and it is net of exactly one thing: benefits you repaid to Social Security, in box 4. It is not net of the Medicare premium, the tax you had withheld, or anything else deducted before the money reached you — those were added back in. On a typical 2025 record that gap is $2,220, so box 5 reads $30,000 while $27,780 actually arrived. The IRS tells you in as many words not to adjust for it.
IRS worksheets read line by line: Social Security Lump-Sum Worksheet 2, Social Security Lump-Sum Worksheet 3 and Social Security Lump-Sum Election Worksheet 4.
Form 1040 for 2025, lines 12 to 38 read line by line: Form 1040 line 25.
Form 1040 for 2025, read line by line: Form 1040 line by line, Form 1040 line 1z and Form 1040 line 6a and 6b.
Read box by box from the IRS instructions: SSA-1099 and RRB-1099 boxes explained.
More IRS forms and schedules, read line by line: Form 4506-T instructions.
The recipient copy of Form 1099-G or 1099-K, read box by box: 1099-G box 1 and 1099-G box 10.
The recipient copy of Form 1099-NEC or 1099-MISC, read box by box: 1099-MISC box 6 and 1099-MISC box 10.
The three boxes, and what “net” actually means
Start with box 3, which the SSA warns you about in its own explanation:
“This figure may not agree with the amounts you actually received because adjustments may have been made to your benefits before you received them.”
IRS, Publication 915, Appendix, Box 3—Benefits Paid
Box 4 is what you paid back to Social Security during the year — returned cheques, overpayment recoveries and the like. And box 5 is one subtraction:
“The figure in this box is the net benefits paid to you for the year. It is the result of subtracting the figure in box 4 from the figure in box 3.”
IRS, Publication 915, Appendix, Box 5—Net Benefits
Box 3 minus box 4. That is the entire definition. The Medicare premium does not appear in it, because the Medicare premium is not in box 4.
Why the deductions are added, not subtracted
Under the “Description of Amount in Box 3” heading, the form lists everything that was taken out before your payment reached the bank: the Medicare premium, voluntary withholding, child support, attorney fees, a workers’ compensation offset. Then it says what it does with them:
“If amounts appear on your Form SSA-1099 next to these items, they will be added to the amount shown in “Paid by check or direct deposit.””
IRS, Publication 915, Appendix, Description of Amount in Box 3
Added. Box 3 is built by taking what you actually received and adding the deductions back on, so it represents the benefit you were entitled to rather than the payment that landed. That is why box 5 is larger than your deposits, and it is not an error.
The instruction most people miss
Immediately above that list sits a tip, and it is unambiguous:
“Don’t reduce the amount of net social security benefits (box 5) by any of the items listed below. Use the amount in box 5 to figure taxable social security.”
IRS, Publication 915, Appendix, Description of Amount in Box 3
So the intuitive correction — “I never got the Medicare money, so I should not be taxed on it” — is exactly the adjustment you are told not to make. Box 5 is the number the worksheets start from:
“Enter the total amount from box 5 of ALL your Forms SSA-1099 and RRB-1099”
IRS, Publication 915, Worksheet A, line A
Reducing it by $2,220 first understates the figure every taxability calculation depends on.
Reconciling the form to your bank account
One year, one beneficiary, Medicare Part B deducted at the published basic rate:
“The basic monthly premium in 2025 was $185.00 for most people”
IRS, Publication 915, Appendix, Medicare premiums deducted from your benefits
| Line | Amount |
|---|---|
| Paid by check or direct deposit (what arrived) | $27,780 |
| Add: Medicare premiums deducted ($185.00 x 12) | $2,220 |
| Box 3 — benefits paid | $30,000 |
| Less: box 4, benefits repaid to SSA | $0 |
| Box 5 — net benefits | $30,000 |
The gap between box 5 and the bank account is $2,220, or 7.4% of the reported benefit, and it is the premium exactly. That premium is not lost for tax purposes — it just belongs somewhere else:
“Premiums you pay for Medicare Part B are a medical expense.”
IRS, Publication 502, Medicare Part B
Which is an itemised deduction subject to its own threshold, not a reduction of box 5. Two different places on the return, and only one of them is right.
Two marks on the form worth knowing
Parentheses around box 5. Rare, and it means the year went backwards:
“If parentheses are around the figure in box 5, it means that the figure in box 4 is larger than the figure in box 3. This is a negative figure and means you repaid more money than you received”
IRS, Publication 915, Appendix, Box 5—Net Benefits
An asterisk after box 3. This one changes what you can do:
“An asterisk (*) after the figure shown in this box means that it includes benefits received in”
IRS, Publication 915, Appendix, Box 3—Benefits Paid
A payment covering earlier years is still taxed in the year you received it by default — but there is an election that lets you test it against the earlier years’ income instead, and on the right facts it removes the tax entirely. That is a page of its own, and the asterisk is the signal to go and read it.
If what you are trying to work out is how much of the benefit is taxable at all, start with the provisional-income thresholds. If a term on the form is unfamiliar, the glossary is the faster route.
The SSA-1099 pages box by box
Each row links to the page that reads one part of the SSA-1099, or the whole form. The right column is the summary each page carries.
| Page | What it covers |
|---|---|
| SSA-1099 and RRB-1099 Boxes Explained, Box by Box | Every box on Form SSA-1099 and Form RRB-1099 that matters when you file: what each amount is and where it goes, with a page for each box. |
| SSA-1099 Box 3: Benefits Paid and Why It Differs From Deposits | SSA-1099 box 3 shows total benefits paid in the year, which may not match what you received. How the box 3 description and the asterisk work (Pub. 915). |
| SSA-1099 Box 4: Benefits Repaid to SSA and Its Description | SSA-1099 box 4 shows what you repaid to the SSA in the year, whenever the benefits were received. How the box 4 description works and how it feeds box 5. |
| SSA-1099 Box 5: Net Benefits (Box 3 Minus Box 4) | SSA-1099 box 5 equals box 3 minus box 4, shown in parentheses if negative. Where to enter it on Notice 703 and Worksheet 1, with a labelled illustration. |
| SSA-1099 Box 6: Voluntary Federal Income Tax Withheld | SSA-1099 box 6 shows federal income tax withheld from your benefits at your request. Where it goes on the return and how Form W-4V fits. |
| SSA-1099 Medicare Premiums Deducted From Benefits | Medicare premiums deducted from your benefits appear inside the SSA-1099 box 3 description, and box 5 is not reduced by them. What Pub. 915 says. |
What this page does not do
- It does not compute how much of your benefit is taxable. That depends on the rest of your income and is a different calculation.
- The Part B figure is the published basic premium. It is higher for late enrolment and for higher incomes, so the gap on your own form will differ and this page should not be read as predicting it.
- It reads the IRS publication, not an SSA page. The Social Security Administration’s own site refused every request from this session, so the box-by-box explanations quoted here are the ones the IRS reproduces.
- It does not cover Form SSA-1042S or the railroad equivalents, which have extra boxes and are not decoded here.
- It does not cover repayments larger than benefits beyond noting the parentheses.
Figures verified against IRS Publication 915 (2025) and IRS Publication 502 (2025) on September 30, 2026.
Sources
Every figure on this page is computed from the text quoted below, as read at the issuing authority on 2026-08-14.
| What it establishes | Source |
|---|---|
| Box 3 will not match your bank statements, and the SSA says so. | IRS, Publication 915, Appendix, Box 3—Benefits Paid |
| The mechanism: deductions are ADDED BACK into box 3, not netted off. | IRS, Publication 915, Appendix, Description of Amount in Box 3 |
| What ‘net’ means in box 5: net of box 4 only. | IRS, Publication 915, Appendix, Box 5—Net Benefits |
| The published basic Part B premium, which is the usual size of the gap. | IRS, Publication 915, Appendix, Medicare premiums deducted from your benefits |
| Where the premium does belong instead. | IRS, Publication 502, Medicare Part B |
| Box 5 is the figure the taxability worksheets start from. | IRS, Publication 915, Worksheet A, line A |
General consumer information, not tax, legal or financial advice. Every quotation above was read from the issuing authority’s own page on 2026-08-14 and forms and instructions change; your own facts decide the outcome, and anything consequential belongs with a preparer or the IRS rather than with a web page.