Updated October 17, 2026. Quick answer: Box 6 of Form RRB-1099 shows the workers’ compensation you received that was used to offset your railroad tier 1 payments. It is listed separately only for your information, because the SSEB amounts in boxes 3 and 5 already include the reduction. If you had no workers’ compensation, box 6 is blank.
What box 6 reports
Publication 915 describes the box: “The figure shown in this box is the amount you received in workers’ compensation benefits during the year that was used to offset the full amount of your tier 1 payments.” It is the sixth item on a form that is mapped in the SSA-1099 and RRB-1099 boxes guide, and it sits between the net benefit in box 5 and the earlier-year boxes 7 to 9.
If it is empty, that is normal. “If you didn’t receive workers’ compensation benefits, box 6 is blank.”
Why it is shown only for your information
The central sentence in the publication: “The SSEB portions of your tier 1 benefits shown in boxes 3 and 5 include amounts by which your SSEB payments were reduced for workers’ compensation benefits.” “Your workers’ compensation amount is shown in this box separately only for your information.”
In other words, box 6 is not an extra amount to add to boxes 3 or 5. The offset is already in those boxes. The gross treatment is also listed in the box 3 deduction list, where the publication names “Workers’ compensation offset (explained in the description of box 6, later).” The box 3 side is on the box 3 page.
The publication’s example, step by step
The publication’s example is a single paragraph; the table below splits it into the pieces it uses.
| Item in the example | What Publication 915 says |
|---|---|
| Tier 1 benefit before the offset | “your tier 1 benefit of $450 a month” |
| Monthly offset | “a $50-a-month workers’ compensation offset” |
| Boxes 3 and 5 | “will show $5,400 ($450 × 12 months) as the SSEB portion of tier 1 benefits paid to you by the RRB” |
| Box 4 | “Box 4 will show zero because you didn’t make any repayments during the year.” |
| Box 6 | “Box 6 of your form will show $600 ($50 workers’ compensation × 12 months).” |
The paragraph then ties the boxes together: “The $5,400 is the amount before any deductions were made for the workers’ compensation offset.” The $400 monthly payment in the example is the $450 benefit reduced by the $50 offset, which is why box 3 and box 5 show a larger figure than the checks received. The $600 in box 6 equals the monthly offset over the twelve months of the example, as the printed arithmetic shows.
Which amount to use for the taxability test
The example ends with a direct instruction: “In figuring if any of your benefits are taxable, you must use $5,400 (box 5) as the amount of the SSEB portion of tier 1 benefits paid to you.” So the box 6 figure is not subtracted from box 5 in the test. The publication frames the test generally: “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.
The net figure itself is explained on the box 4 and box 5 page. The overall return is Form 1040, and the social security tax torpedo page covers how added income affects the taxable share of benefits.
Related boxes and forms
The Medicare premium total is a different kind of figure, and the publication handles it in box 11: “This is only for informational purposes and the RRB does not report this amount to the IRS.” is the sentence for box 11. Those are explained on the box 10 and box 11 page.
The railroad pension tiers that do not appear here are discussed on the railroad retirement tier 1 and tier 2 taxation page. The publication’s own scope statement is “This publication doesn’t cover the tax rules for the following railroad retirement benefits.” It then lists the NSSEB portion of tier 1 benefits, tier 2 benefits, vested dual benefits, and supplemental annuity benefits.
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 6 is labelled as the workers’ compensation offset for 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
- Adding box 6 on top of boxes 3 or 5. The publication says those boxes “include amounts by which your SSEB payments were reduced for workers’ compensation benefits”.
- Subtracting box 6 from box 5 before the taxability test. The example says “you must use $5,400 (box 5)” as the amount paid.
- Reading a blank box 6 as a missing figure. The publication says “If you didn’t receive workers’ compensation benefits, box 6 is blank.”
Related: railroad retirement explained, how railroad retirement is calculated, Form 1040, and the social security tax torpedo.
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.