You only need to attach a W-2 to your California tax return if you file on paper. The Franchise Tax Board’s instructions for Form 540 tell paper filers to attach every W-2, W-2G, 1099, 592-B, and 593 showing California withholding to the lower front of the return.1State of California Franchise Tax Board. 2025 Instructions for Form 540 California Resident Income Tax Return If you e-file, your software transmits the wage and withholding data electronically and no physical W-2 is sent.
How to Attach a W-2 to a Paper Return
Use Copy 2 of your W-2, which is the copy labeled for state and local tax filing. Attach it to the lower front page of Form 540, along with any other forms that show California income tax withheld.1State of California Franchise Tax Board. 2025 Instructions for Form 540 California Resident Income Tax Return
The FTB also spells out how to assemble the rest of the return. Enclose any payment without stapling it. Stack all six sides of Form 540 in numerical order. Put California supporting schedules behind Form 540, then a copy of your federal return behind those.1State of California Franchise Tax Board. 2025 Instructions for Form 540 California Resident Income Tax Return
Where you mail it depends on whether you owe. Refund and zero-balance returns go to Franchise Tax Board, PO Box 942840, Sacramento, CA 94240-0001. Returns with a payment go to PO Box 942867, Sacramento, CA 94267-0001.1State of California Franchise Tax Board. 2025 Instructions for Form 540 California Resident Income Tax Return
Why E-Filers Don’t Send a W-2
When you e-file, the software pulls the key figures from your W-2, including your employer’s identification number, total wages, and California tax withheld, and sends them straight to the FTB. The agency then matches those numbers against wage and withholding records employers report to the California Employment Development Department.2Employment Development Department. California State Payroll Taxes – Overview Keep your W-2 in your own records, but nothing is mailed.
California offers free e-filing directly through the FTB called CalFile. For the 2025 tax year, CalFile is available to residents with federal adjusted gross income up to $252,203 (single), $378,310 (head of household), or $504,411 (married filing jointly).3State of California Franchise Tax Board. CalFile Qualifications 2025 It doesn’t cover every situation. You can’t use it if you have capital gains, business income, rental income, or certain other complexities. For a straightforward W-2 wage earner, it removes the attachment question entirely.
If a paid preparer handles your return, it’s almost certainly going in electronically. California requires preparers who file more than 100 individual state returns a year and use tax software to e-file all of them, with a $50 per-return penalty for paper filing in violation of the rule.4State of California Franchise Tax Board. 2025 Handbook for Authorized e-file Providers FTB Publication 1345 You can ask your preparer to opt you out, but paper is now the exception.
If Your W-2 Never Arrived
Employers must deliver W-2s to employees by January 31.5Social Security Administration. Deadline Dates to File W-2s If yours hasn’t arrived by mid-February, ask your employer for a reissued copy first. Some employers or payroll providers charge a small fee for a duplicate, often somewhere between $0 and $40.
If your employer won’t cooperate, call the IRS at 800-829-1040. The IRS will send your employer a letter requiring a corrected W-2 within ten days and will send you federal Form 4852 as a substitute.6Internal Revenue Service. W-2 – Additional, Incorrect, Lost, Non-Receipt, Omitted The FTB confirms the same path: after February, contact the IRS if the W-2 still hasn’t shown up.7State of California Franchise Tax Board. 2025 California Form 3525 Substitute for Form W-2, Wage and Tax Statement
For the California side, if the deadline is closing in and you still don’t have the W-2, use FTB Form 3525 as a substitute. Fill in your best estimate of wages and withholding from your final pay stub, and explain why the W-2 wasn’t available and what you did to get it. Attach Form 3525 to your Form 540, 540 2EZ, or 540NR the same way you’d attach a W-2.7State of California Franchise Tax Board. 2025 California Form 3525 Substitute for Form W-2, Wage and Tax Statement Using an estimate can slow refund processing while the FTB verifies the numbers.
If You Forgot to Attach the W-2
If you already mailed your paper return and realized the W-2 wasn’t in the envelope, do not mail the W-2 separately and do not send another copy of the return. The FTB says to wait until they request the missing document.1State of California Franchise Tax Board. 2025 Instructions for Form 540 California Resident Income Tax Return Loose forms sent on their own can’t be matched to a filed return through normal processing.
How Long to Keep Your W-2
The FTB can examine your return and issue a Notice of Proposed Assessment within four years of either the return’s due date or the date you filed, whichever is later.8Franchise Tax Board. Keeping Your Tax Records Keep your W-2s and returns for at least that long. Hang on to them longer if you have reason to think a federal adjustment could later change your California liability.