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.
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.
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.
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.