How to Complete and File the California CDTFA-401-A Sales Tax Return

To file the CDTFA-401-A sales tax return in California, report your total sales for the reporting period, subtract documented nontaxable transactions, apply the state, county, local, and district tax rates to what remains, and submit the return with payment through the California Department of Tax and Fee Administration’s online portal at onlineservices.cdtfa.ca.gov. Paper returns go to PO Box 942879, Sacramento, CA 94279-8062. You must file for every assigned reporting period, even when you had no sales.¹

What You Need Before You Start

You cannot file this return without a seller’s permit, or a Certificate of Registration – Use Tax if you’re an out-of-state seller. The permit is free through the CDTFA’s online registration system, and your permit number and account number appear on every return.²

Pull these records together for the period you’re filing:

Total gross receipts, including cash, credit, lease, and rental income, taxable or not.³
Valid resale certificates from buyers who purchased goods to resell.⁴
Shipping documentation for goods sent out of state or to foreign destinations.⁵
Purchase invoices for items bought from out-of-state vendors that didn’t charge California tax (you owe use tax on those).
The district tax rates that apply to each of your business locations. Look them up at maps.cdtfa.ca.gov.⁶

Hold on to all of it for at least four years, and longer if you’re under audit.⁷

When the Return Is Due

The CDTFA assigns your filing frequency at registration: quarterly prepay, quarterly, monthly, fiscal yearly, or yearly, based on your reported or anticipated tax liability.⁸ Under Revenue and Taxation Code Section 6451, the return and payment are due by the last day of the month after each reporting period closes.⁹ So a quarterly filer covering January through March files by April 30. Weekends and state holidays push the deadline to the next business day.¹

Quarterly prepayment filers pay monthly during the quarter (each prepayment due by the 24th of the following month) and reconcile on the CDTFA-401-A after the quarter ends. On the return itself, enter all three months of sales, not the leftover balance.¹

A period with zero sales still requires a return. Skipping it counts as a late filing and can trigger a penalty, though you don’t need to submit any payment.¹

Completing the Return Line by Line

Filing online is easier because the system calculates tax as you go and flags likely omissions.³ The same numbered lines appear whether you file online or on paper.

Total Sales and Deductions

Line 1 is your total sales for the period, including lease and rental receipts.⁴ Then you subtract nontaxable transactions, each on its own line. Common deductions:

Sales for resale, backed by a valid resale certificate.⁵
Sales to the U.S. government.
Goods shipped to customers outside California (interstate or foreign commerce).
Nontaxable food products sold for home consumption.
Repair and installation labor when separately stated on the invoice.

Only claim a deduction if you have the paperwork to prove it. If an audit reverses the deduction, you owe the tax and interest.

Applying the Tax Rates

The statewide minimum combined rate is 7.25%, layered on the form as:

Line 13 — State tax: 6.00%
Line 14 — County tax: 0.25%
Line 15 — Local tax: 1.00%

Line 16 covers district taxes, which vary by location and often push the combined rate above 7.25%. If any of your sales occurred in a district tax area, you also complete Schedule A2 (CDTFA-531-A2), applying each district’s rate to sales made there.⁵ Verify the rate for every location, not just your headquarters. This is where paper filers most often go wrong.

After you subtract any credits or prepayments already remitted, Line 17 gives you the total tax due.

Partial Exemption for Manufacturing and R&D

If your business is primarily engaged in manufacturing, research and development, or electric power generation, qualifying equipment purchases get a partial exemption of 3.9375% off the purchase price, in effect through June 30, 2030.¹⁰ You claim it by giving the seller a completed CDTFA-230-M certificate. The remaining state, local, and district taxes still apply. If you take the equipment out of California within a year, convert it to a non-qualifying use, or exceed the $200 million annual cap, you report and pay the exempted state tax on your return.

Submitting and Paying

To file online, log in at onlineservices.cdtfa.ca.gov, choose the account and reporting period, enter your figures, review the calculated tax, and sign electronically under penalty of perjury.⁵ Save the confirmation number as proof of filing.¹¹

Paper returns go to the California Department of Tax and Fee Administration, PO Box 942879, Sacramento, CA 94279-8062, and must be postmarked by the due date.¹²

You can pay by ACH debit through the portal, which pulls funds from your bank account.¹³ EFT payments initiated on the due date must be completed by 3:00 p.m. Pacific time; non-EFT online payments run until midnight Pacific.¹ By check or money order, make payment out to the California Department of Tax and Fee Administration, write your account number on it, and mail with a voucher to PO Box 942879, Sacramento, CA 94279-7072.¹²

If your average monthly tax liability reaches $10,000, EFT is mandatory. The CDTFA reviews accounts annually and notifies businesses that cross the threshold.¹⁴

If You File or Pay Late

Both a late return and a late payment carry a 10% penalty under Revenue and Taxation Code Section 6591. When both apply to the same return, the combined penalty caps at 10% of the tax due; the two do not stack.¹⁵

Interest accrues from the original due date until you pay. For 2026, the CDTFA’s debit interest rate is 10% annually, or a monthly factor of 0.00833 per month or partial month unpaid.¹⁶ On a $5,000 tax bill paid three months late, that works out to about $125 in interest on top of the $500 penalty.

Asking for Penalty Relief

The CDTFA can waive a penalty for reasonable cause: you exercised ordinary care and the failure wasn’t willful neglect. Natural disasters, serious illness, and death in the family are typical grounds.¹⁷ Submit the request through the online portal (under “I Want To,” then “More,” then “Submit a Relief Request”) or on paper form CDTFA-735 mailed to the unit managing your account.¹⁸ Identify the specific penalty, explain the facts, and attach documentation. The CDTFA won’t act on your request until the underlying tax is paid in full.

Fixing a Filed Return

If you spot an error after filing, amend the return rather than wait. Online: log in, pick the period, choose “Amend Return” under “I Want To,” enter the corrected figures, and submit. Interest and penalty adjustments post automatically, usually overnight.¹⁹

For older periods not available online, copy the original return, write “AMENDED RETURN” at the top, cross out the wrong figures, write in the correct ones, attach a cover letter explaining the changes, and mail the package with any additional payment to PO Box 942879, Sacramento, CA 94279-7072.¹⁹ If the amendment shows an overpayment, it counts as a claim for refund automatically.

Watch the refund deadline: generally three years from the return’s due date, or six months from the date of overpayment, whichever is later.²⁰

Out-of-State and Marketplace Sellers

Out-of-state retailers whose total sales of tangible goods delivered into California exceed $500,000 in the current or preceding calendar year must register with the CDTFA and collect use tax, even without a physical presence in the state. That threshold includes sales made through marketplace platforms.²¹

Sellers who work only through a marketplace facilitator like Amazon or Etsy generally do not need to register for those transactions; the facilitator collects and remits the tax. If you also sell directly to California customers outside the marketplace, you need your own seller’s permit and file returns covering the direct sales.²²

1
California Department of Tax and Fee Administration. Filing Dates for Sales and Use Tax Returns
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California Department of Tax and Fee Administration. Obtaining a Sellers Permit
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California Department of Tax and Fee Administration. Instructions for Completing CDTFA-401-A, State, Local, and District Sales and Use Tax Return
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California Department of Tax and Fee Administration. Online Filing Instructions – Sales and Use Tax Return
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California Department of Tax and Fee Administration. CDTFA-401-A Sales Tax Return
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California Department of Tax and Fee Administration. Find a Sales and Use Tax Rate
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California Department of Tax and Fee Administration. Sales and Use Tax Records Publication 116 – Retaining Records
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California Department of Tax and Fee Administration. Return Prepayments
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California Department of Tax and Fee Administration. Revenue and Taxation Code 6451 – Due Date
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California Department of Tax and Fee Administration. Partial Exemption Certificate for Manufacturing and Research and Development Equipment
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California Department of Tax and Fee Administration. Online Services – File a Return
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California Department of Tax and Fee Administration. Online Services – Make a Payment
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California Department of Tax and Fee Administration. Electronic Funds Transfer Payment Options
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California Department of Tax and Fee Administration. Electronic Funds Transfer
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California Department of Tax and Fee Administration. Sales and Use Tax Law – Section 6591
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California Department of Tax and Fee Administration. Interest Rates
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California Department of Tax and Fee Administration. Rule 35048 Authority to Grant Relief of Penalty for Reasonable Cause and Contents of a Request for Such Relief
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California Department of Tax and Fee Administration. Request for Relief from Penalty, Collection Cost Recovery Fee, and/or Interest
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California Department of Tax and Fee Administration. Amend a Return
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California Department of Tax and Fee Administration. Filing a Claim for Refund
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California Department of Tax and Fee Administration. Use Tax Collection Requirements Based on Sales into California Due to the Wayfair Decision
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California Department of Tax and Fee Administration. Tax Guide for Marketplace Facilitator Act