Updated October 21, 2026. Quick answer: Worksheet 4 in Publication 915 figures your taxable benefits under the lump-sum election: the 2025 benefits without the back payment, plus the extra from Worksheets 2 and 3. Compare line 21 with Worksheet 1, line 19. If line 21 is smaller you can elect it by checking the box on Form 1040 line 6c.
What Worksheet 4 is for
The publication lays out the test: “Compare the taxable benefits on line 19 of Worksheet 1 with the taxable benefits on line 21 of Worksheet 4.” “If the taxable benefits on Worksheet 4 are lower than the taxable benefits on Worksheet 1, you can elect to report the lower amount on your return.” The lines it feeds are at Form 1040 lines 6a and 6b.
The worksheet line by line
| Line | What the worksheet says |
|---|---|
| Before you start | “Complete Worksheet 1 and Worksheets 2 and 3 as appropriate before completing this worksheet.” |
| 1 | “Enter the total amount from box 5 of ALL your Forms SSA-1099 and RRB-1099 for 2025, minus the lump-sum payment for years before 2025” |
| 2 | “Multiply line 1 by 50% (0.50)” |
| 3 to 5 | Copied from lines 3, 4 and 5 of Worksheet 1: “Enter the amount from Worksheet 1, line 3” |
| 6 | “Combine lines 2, 3, 4, and 5 above” |
| 7 | “Enter the amount from Worksheet 1, line 7” |
| 8 | “Subtract line 7 from line 6” |
| 9 | “Enter the amount from Worksheet 1, line 9.” |
| 10 | “Is the amount on line 8 more than the amount on line 9?” No: line 19 is -0- and you go to line 20. Yes: “Subtract line 9 from line 8” |
| 11 | “Enter the amount from Worksheet 1, line 11” |
| 12 | “Subtract line 11 from line 10. If zero or less, enter -0-” |
| 13 | “Enter the smaller of line 10 or line 11” |
| 14 | “Multiply line 13 by 50% (0.50)” |
| 15 | “Enter the smaller of line 2 or line 14” |
| 16 | “Multiply line 12 by 85% (0.85). If line 12 is zero, enter -0-” |
| 17 | “Add lines 15 and 16” |
| 18 | “Multiply line 1 by 85% (0.85)” |
| 19 | “Enter the smaller of line 17 or line 18” |
| 20 | “Enter the total of the amounts from Worksheet 2, line 21, and Worksheet 3, line 14, for all earlier years for which the lump-sum payment was received” |
| 21 | “Taxable benefits under lump-sum election method. Add lines 19 and 20” |
The IRS example: Terry Jackson
Terry, single, received a $6,000 lump sum in 2025 of which $2,000 was for 2024 and $4,000 for 2025, plus $5,000 of other benefits that year. Worksheet 2 added nothing for 2024. The inputs below are the IRS’s, with the arithmetic shown.
| Item | Illustration |
|---|---|
| Line 1 (the IRS example: $11,000 received in 2025 less the $2,000 for 2024) | $9,000 (computed) |
| Line 2, computed: line 1 x 50% | $4,500 (computed) |
| Line 3 (from Worksheet 1, the IRS example) | $25,500 |
| Line 6, computed: line 2 + line 3 (lines 4 and 5 are zero) | $30,000 (computed) |
| Line 9 (single base amount) | $25,000 |
| Line 10, computed: line 8 minus line 9 | $5,000 (computed) |
| Line 11 (single) | $9,000 |
| Line 13, computed: smaller of line 10 and line 11 | $5,000 (computed) |
| Line 14, computed: line 13 x 50% | $2,500 (computed) |
| Line 15, computed: smaller of line 2 and line 14 | $2,500 (computed) |
| Line 17, computed: line 15 + line 16 (line 16 is zero) | $2,500 (computed) |
| Line 18, computed: line 1 x 85% | $7,650 (computed) |
| Line 19, computed: smaller of line 17 and line 18 | $2,500 (computed) |
| Line 21, computed: line 19 + line 20 (line 20 is zero) | $2,500 (computed) |
Terry’s line 21 of $2,500 is lower than the regular-method result on Worksheet 1, so Terry elects the lump-sum method, as the publication shows.
Making the election
The worksheet ends with the steps: “Check the box on Form 1040 or 1040-SR, line 6c.” (the line reads “If you elect to use the lump-sum election method, check here (see instructions)”) Then “Enter the amount from Worksheet 1, line 1, on Form 1040 or 1040-SR, line 6a;” and “Enter the amount from line 21 above on Form 1040 or 1040-SR, line 6b;” The earlier-year inputs come from Worksheet 2 and Worksheet 3.
What the publication says about the paperwork
“Don’t attach the completed worksheets to your return. Keep them with your records.” “Once you elect this method of figuring the taxable part of a lump-sum payment, you can revoke your election only with the consent of the IRS.”
Edition and line numbers
This page reads Publication 915 (2025), the current file irs.gov served on 2026-10-21 (sha256 in the kit data). The worksheets in it are for the 2025 return, filed in 2026. Check the tax year printed on the worksheet in your own copy and use that year’s line numbers and dollar amounts, because a different year’s worksheet can word its lines differently.
Common mistakes
- Starting before Worksheet 1 is done. Lines 3, 4, 5, 7, 9 and 11 are copied from it.
- Leaving the back payment in line 1. The line is “minus the lump-sum payment for years before 2025”
- Electing when line 21 is not smaller than Worksheet 1, line 19. Then the instruction is that you “Don’t use this method to figure your taxable benefits.”
Related: Form 1040 lines 6a and 6b, Social Security Benefits Worksheet, Form SSA-1099 box 3, and Form SSA-1099 box 5.
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Answer againSources
- Publication 915 (2025), Social Security and Equivalent Railroad Retirement Benefits: https://www.irs.gov/pub/irs-pdf/p915.pdf
- Form 1040 (2025), U.S. Individual Income Tax Return: https://www.irs.gov/pub/irs-pdf/f1040.pdf
Read from the IRS documents linked above on October 21, 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.