Updated October 21, 2026. Quick answer: Worksheet 2 in Publication 915 refigures the taxable part of a back payment of social security for one earlier year after 1993, using that earlier year’s income. Its line 21 is the extra taxable benefit, and it is carried to line 20 of Worksheet 4. If line 8 is not above the base amount on line 9, line 21 is zero.
What Worksheet 2 is for
If you received a back payment in 2025 that covers an earlier year, the publication says “Use Worksheet 2 if your lump-sum payment was for a year after 1993.” You fill one in for each earlier year, then feed the results to Worksheet 4. The first line of the return that is affected is Form 1040 lines 6a and 6b.
The worksheet line by line
| Line | What the worksheet says |
|---|---|
| Which year | “Worksheet 2. Figure Your Additional Taxable Benefits (From a Lump-Sum Payment for a Year After 1993)” |
| 1 | “Enter the total amount from box 5 of ALL your Forms SSA-1099 and RRB-1099 for the earlier year, plus the lump-sum payment for the earlier year received after that year” |
| 2 | “Multiply line 1 by 50% (0.50)” |
| 3 | “Enter your adjusted gross income for the earlier year” |
| 4 | “Enter the total of any exclusions/adjustments you claimed in the earlier year for:” the list includes adoption benefits (Form 8839), qualified U.S. savings bond interest (Form 8815) and foreign earned income or housing (Form 2555). |
| 5 | “Enter any tax-exempt interest received in the earlier year” |
| 6 | “Add lines 2 through 5” |
| 7 | “Enter your taxable benefits for the earlier year that you previously reported” |
| 8 | “Subtract line 7 from line 6” |
| 9 | “Married filing jointly, enter $32,000; or” “Single, head of household, qualifying surviving spouse, married filing separately and you lived apart from your spouse for all of the earlier year, enter $25,000” |
| 10 | “Is the amount on line 8 more than the amount on line 9?” No: skip to line 21 and enter -0-. Yes: “Subtract line 9 from line 8” |
| 11 | “Enter $12,000 if married filing jointly for the earlier year; or $9,000 if single, head of household, qualifying surviving spouse, or married filing separately and you lived apart from your spouse for all of the earlier year” |
| 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 | “Refigured taxable benefits. Enter the smaller of line 17 or line 18” |
| 20 | “Enter your taxable benefits for the earlier year (or as refigured due to a previous lump-sum payment for the year)” |
| 21 | “Additional taxable benefits. Subtract line 20 from line 19.” “Also enter this amount on Worksheet 4, line 20” |
The IRS example: a payment that adds nothing
Publication 915 follows Terry Jackson, single, who received $2,000 of a 2025 lump sum for 2024. The inputs are the IRS’s; the arithmetic is shown.
| Item | Illustration |
|---|---|
| Line 1: the 2024 part of the lump sum (the IRS example) | $2,000 |
| Line 2, computed: line 1 x 50% | $1,000 (computed) |
| Line 3: 2024 adjusted gross income (the IRS example) | $23,000 |
| Line 6, computed: line 2 + line 3 (lines 4 and 5 are zero) | $24,000 (computed) |
| Line 8, computed: line 6 minus line 7 (line 7 is zero) | $24,000 (computed) |
| Line 9: single base amount | $25,000 |
| Line 10: is line 8 more than line 9? | No, so line 21 is -0- |
Terry’s 2024 figures stay under the $25,000 base amount, so the refigured 2024 tax on benefits adds nothing and Worksheet 2 ends at line 21 with -0-.
An example that does add taxable benefit
Illustration, not an IRS example. Every input is invented, and the filer is single with no benefits previously reported for the earlier year.
| Item | Illustration |
|---|---|
| Line 1 (invented) | $4,000 |
| Line 2, computed: line 1 x 50% | $2,000 (computed) |
| Line 3: adjusted gross income for the earlier year (invented) | $40,000 |
| Line 6, computed: line 2 + line 3 | $42,000 (computed) |
| Line 8, computed: line 6 minus line 7 (line 7 is zero) | $42,000 (computed) |
| Line 10, computed: line 8 minus line 9 (the $25,000 single base) | $17,000 (computed) |
| Line 12, computed: line 10 minus line 11 ($9,000) | $8,000 (computed) |
| Line 13, computed: smaller of line 10 and line 11 | $9,000 (computed) |
| Line 14, computed: line 13 x 50% | $4,500 (computed) |
| Line 15, computed: smaller of line 2 and line 14 | $2,000 (computed) |
| Line 16, computed: line 12 x 85% | $6,800 (computed) |
| Line 17, computed: line 15 + line 16 | $8,800 (computed) |
| Line 18, computed: line 1 x 85% | $3,400 (computed) |
| Line 19, computed: smaller of line 17 and line 18 | $3,400 (computed) |
| Line 21, computed: line 19 minus line 20 (line 20 is zero) | $3,400 (computed) |
The $3,400 on line 21 is the extra taxable benefit this earlier year contributes. It cannot be more than 85 percent of the earlier year’s benefits, which is what line 18 enforces.
Where it goes next
Line 21 goes to line 20 of Worksheet 4, which adds it to the current-year figure and compares the total with Worksheet 1. If you elect that method, Form 1040 line 6c reads “If you elect to use the lump-sum election method, check here (see instructions)”. A payment for 1993 or an earlier year uses Worksheet 3 instead.
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
- Filing an amended return for the earlier year. “Don’t file an amended return for this earlier year.”
- Using one worksheet for several years. “Complete a separate Worksheet 2 or Worksheet 3 for each earlier year”
- Using the current year’s income on line 3. The line asks for the adjusted gross income of the earlier year.
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.