Updated October 24, 2026. Quick answer: Line 6 of California Schedule CA (540) is where you adjust the social security benefits that appear on your federal return. Column A repeats the federal amounts, and the booklet tells you what goes in column B. The schedule’s line 27 total then carries to Form 540 line 14 or line 16.
What this line does
On the schedule the line is labelled “Social security benefits” and it has a line 6a box and a line 6b box in the federal column. The booklet’s heading for the instructions is “Social Security Benefits” under line 6, and it is part of Section A, “Income from federal Form 1040 or 1040-SR”.
Schedule CA (540) as a whole is described this way: “Use Schedule CA (540) to make adjustments to your federal adjusted gross income and to your federal itemized deductions using California law.” For the lines just above this one see Schedule CA (540) lines 4 and 5; the whole form is laid out in California Form 540 line by line.
Who it applies to
The booklet’s line 6 rule is “California excludes U.S. social security benefits or equivalent Tier 1 railroad retirement benefits from taxable income.” and the entry it asks for is “the amount of taxable U.S. social security benefits or equivalent Tier 1 railroad retirement benefits shown on line 6b, column A.”
The state-level view of this topic is in whether California taxes Social Security, and the federal lines that feed column A are in Form 1040 line 6a and 6b.
What the instructions say
| Line | What the form says |
|---|---|
| Purpose | “Use Schedule CA (540) to make adjustments to your federal adjusted gross income and to your federal itemized deductions using California law.” |
| Form 540 attachment | “Attach this schedule behind Form 540, Side 6 as a supporting California schedule.” |
| Section A heading | “Income from federal Form 1040 or 1040-SR” |
| Line 6 label | “Social security benefits” (the form shows a line 6a and a line 6b) |
| Column A | “Enter in Section A, line 1a through line 7a, and Section B, line 1 through line 9a the same amounts entered on your federal Form 1040, U.S. Individual Income Tax Return, or Form 1040-SR” |
| Columns B and C | “Use these columns to enter subtractions and additions to the federal amounts in column A that are necessary because of differences between California and federal law.” |
| Sign of amounts | “Enter all amounts as positive numbers unless instructed otherwise.” |
| Line 6 rule | “California excludes U.S. social security benefits or equivalent Tier 1 railroad retirement benefits from taxable income.” |
| Line 6 entry | “Enter in column B the amount of taxable U.S. social security benefits or equivalent Tier 1 railroad retirement benefits shown on line 6b, column A.” |
| Line 27 total | “Subtract line 26 from line 10 in column B and column C.” |
| Line 27 to Form 540, line 14 | “Line 27, column B to Form 540, line 14.” |
| Line 27 to Form 540, line 16 | “Line 27, column C to Form 540, line 16.” |
Lines 4 and 5 of the same section are covered on the Schedule CA (540) lines 4 and 5 page.
The figures the form prints
The line 6 instruction is built from line references rather than a limit: “shown on line 6b, column A” and the line 27 carry sentences quoted in the table.
Where the result goes next
Line 6 is one of many lines that roll into the totals. The booklet says “Subtract line 26 from line 10 in column B and column C.” and then “Also, transfer the amount from:” “Line 27, column B to Form 540, line 14.” and “Line 27, column C to Form 540, line 16.”
It adds a rule for negative totals: “If column B is a negative number, transfer the amount as a positive number to Form 540, line 16.” and “If column C is a negative number, transfer the amount as a positive number to Form 540, line 14.”
The next steps on the state return are described on the pages for Form 540 lines 14 and 16 in California Form 540 line by line. The federal total comes from Form 1040 lines 9, 10 and 11.
Edition and line numbers
This page reads California 540 Forms and Instructions, 2025 Personal Income Tax Booklet for tax year 2025, the current file the Franchise Tax Board served on 2026-10-24. Check the edition printed on your own form and use that edition’s line numbers.
Common mistakes
- Putting the social security amount in the wrong column. The booklet says “Enter in column B the amount of taxable U.S. social security benefits”.
- Changing the federal amounts in column A. The booklet says to enter “the same amounts entered on your federal Form 1040”.
- Entering a negative number in the wrong place when the totals come out negative. The booklet says “If column B is a negative number, transfer the amount as a positive number to Form 540, line 16.”
Related: whether California taxes Social Security, Schedule CA (540) lines 4 and 5, Form 1040 line 6a and 6b, and Form 1040 lines 9, 10 and 11.
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- California 540 Forms and Instructions, 2025 Personal Income Tax Booklet, Franchise Tax Board: www.ftb.ca.gov
- Related official page (not quoted): Franchise Tax Board, 2025 Personal Income Tax Booklet page: www.ftb.ca.gov
Read from the state revenue documents linked above on October 24, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer or the state revenue department is the right place to confirm anything consequential.