Updated October 17, 2026. Quick answer: Box 3 of Form RRB-1099 shows the gross social security equivalent benefit (SSEB) portion of tier 1 railroad retirement benefits paid to you in the year. It is a gross figure, so it is larger than the money that reached your bank account when Medicare premiums or tax were taken out. It is a starting point for working out whether any benefits are taxable on Form 1040.
What box 3 reports
Publication 915 describes the box in these words: “The figure shown in this box is the gross SSEB portion of tier 1 benefits or special guaranty benefits paid to you in 2025.” The term SSEB comes from the publication’s introduction: “Equivalent tier 1 railroad retirement benefits are the part of tier 1 benefits that a railroad employee or beneficiary would have been entitled to receive under the social security system.” “They are commonly called the social security equivalent benefit (SSEB) portion of tier 1 benefits.”
Form RRB-1099 goes to people who had activity in that portion. “If you received, repaid, or had tax withheld from the SSEB portion of tier 1 railroad retirement benefits or special guaranty benefits during 2025, you will receive Form RRB-1099.” This page covers box 3 only. Boxes 4 and 5 are on the repaid and net benefit page, and the whole form is laid out in the SSA-1099 and RRB-1099 boxes guide.
Before and after which deductions
The word gross is defined by a list. “It is the amount before any deductions were made for” the items in the left column below, and “The figure in box 3 is the amount after any deductions were made for” the items in the right column.
| Box 3 is the amount BEFORE these deductions | Box 3 is the amount AFTER these deductions |
|---|---|
| Federal income tax withholding | Social security benefits |
| Medicare premiums | Age reduction |
| Overall minimum assignment payments | Public service pensions or public disability benefits |
| Recovery of an overpayment, including recovery of Railroad Unemployment Insurance Act benefits received while awaiting payment of your railroad retirement annuity | Dual railroad retirement entitlement under another RRB claim number |
| Workers’ compensation offset (explained under box 6) | Work deductions |
| Legal Process Garnishment payments | Actuarial adjustment |
| Annuity waiver | |
| Legal Process Partition payments |
In plain terms, deductions such as Medicare premiums and federal income tax withholding are not subtracted from box 3, so the amount can be higher than the payments you actually received. Deductions in the right column, such as age reduction, are already reflected, so box 3 is lower than the full annuity before those adjustments.
Social security paid through the RRB is not here
A common confusion is where a railroad retiree’s social security check is reported. The publication warns: “Caution: Social security benefits paid through the RRB aren’t reported on Form RRB-1099 or RRB-1042S.” “They are reported on Form SSA-1099 or SSA-1042S issued by the SSA.” If you receive both kinds of benefit, you hold two different forms. The social security side is read box by box in the SSA-1099 box 3 page and the SSA-1099 box 5 page.
The publication also separates the SSEB portion from the rest of tier 1. “If you received, repaid, or had tax withheld from any NSSEB portion of tier 1 benefits, tier 2 benefits, vested dual benefits, or supplemental annuity benefits during 2025, you will receive Form RRB-1099-R, Annuities or Pensions by the Railroad Retirement Board.” “For more information concerning Form RRB-1099-R, see Pub. 575.” How the tiers are taxed is discussed on the railroad retirement tier 1 and tier 2 taxation page.
Example 1 in the publication: unemployment benefits deducted
The publication’s first example shows why box 3 can exceed what you were paid. “Instead of receiving $1,527 ($509 × 3 months), you received $1,227 ($1,527 − $300).” “Box 3 of your Form RRB-1099 will show $5,599 ($509 × 11 months) as the gross SSEB portion of tier 1 benefits paid to you in 2025, even though you didn’t actually receive that amount.”
The reason is given right after: “This is because box 3 shows the gross amount of your benefits before any reductions were made for the unemployment benefits paid to you.” The $300 of Railroad Unemployment Insurance had been paid for January through March, and the first retirement payment arrived in April. The arithmetic in this example is the publication’s own; no figure here is a rule for any other case.
Example 2 in the publication: Medicare premiums and the NSSEB portion
The second example splits one tier 1 payment into two forms. “Your $600 monthly tier 1 benefits consist of an SSEB portion of $250 and an NSSEB portion of $350.” “Box 3 of your Form RRB-1099 will show the gross SSEB portion of tier 1 benefits of $3,000 ($250 × 12 months) because it’s the gross SSEB amount before deductions for your Medicare premiums.”
The same example places the premiums in a different box: “Box 11 of your Form RRB-1099 will show your Medicare premiums” for the months it describes. The rest goes to the other form: “The remainder of your tier 1 payments, the NSSEB portion of $4,200 ($350 × 12 months), will be shown on the Form RRB-1099-R that you will receive along with your Form RRB-1099.” Box 11 is read on the box 10 and box 11 page.
Earlier years are inside box 3
Box 3 is not limited to payments for the current year. “The figure in box 3 includes any lump-sum benefit payment you received in 2025 that is for an earlier year after 1983.” “If you received a payment for an earlier year, it will be shown in box 7, 8, or 9”. Those boxes and the election the publication mentions are explained on the boxes 7, 8 and 9 page.
Where the amount goes
Box 3 is not typed onto Form 1040 on its own. The publication tests benefits as a group: “To find out whether any of your benefits shown on Forms SSA-1099 and RRB-1099 may be taxable, compare the base amount (explained later) for your filing status with the total of” one-half of your benefits plus your other income. “If the total is more than your base amount, part of your benefits may be taxable.” The publication’s worksheets start from box 5, the net figure, which is explained on the box 4 and box 5 page. See Form 1040 for the return itself and the social security tax torpedo page for how added income interacts with benefits.
One more point applies to every box. “The RRB will issue a corrected Form RRB-1099 or RRB-1042S if there is an error in the original.” “A corrected Form RRB-1099 or RRB-1042S is indicated as “CORRECTED” and replaces the corresponding original Form RRB-1099 or RRB-1042S.” If you hold two versions of the same year’s form, “You must use the latest corrected Form RRB-1099 or RRB-1042S you received”.
Edition and box numbers
The primary read for this page is Publication 915, Social Security and Equivalent Railroad Retirement Benefits, the version written for 2025 returns, and its Appendix section on Form RRB-1099 that prints the 2025 form. The publication states its scope this way: “This section explains the items shown on Form RRB-1099.” irs.gov was serving that version at its current publication address on 2026-10-17. No other edition of the publication was compared for this page, so nothing here is a statement about a later tax year. Box 3 is labelled as the gross SSEB portion of tier 1 paid in the year printed on the form; on the sample form in the publication that year is 2025. The publication also advises: “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 form you received before relying on the box numbers and years described here.
Common mistakes
- Treating box 3 as the money deposited. The box is the amount “before any deductions were made for” items such as Medicare premiums and tax withholding.
- Looking for social security checks on this form. “Social security benefits paid through the RRB aren’t reported on Form RRB-1099”, so a separate SSA-1099 is the place to look.
- Expecting every railroad payment to be in box 3. Only the SSEB portion is; the NSSEB portion is “shown on the Form RRB-1099-R”.
Related: railroad retirement tier 1 and tier 2 taxation, the social security tax torpedo, Form 1040, and receiving railroad retirement and social security.
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.