Key takeaways
- Check the reporting basis in the client's CDTFA account before setting any due date.
- Quarterly Prepay filers owe two prepayments a quarter, and the October and November prepayments fall due in late November and December 2026.
- A late return and a late payment together are capped at 10 percent of the tax due for the period.
- Look up the district rate by address, because the statewide base rate of 7.25 percent is only the first layer.
Start with the reporting basis, not the form
Every California seller receives a reporting basis when CDTFA registers the seller's permit. CDTFA's new permit holder page lists five: Quarterly Prepay, Quarterly, Monthly, Yearly and Fiscal Yearly. The basis sets the due dates and decides whether prepayments are required, so check it in the client's CDTFA online account before building anything for the period.
Two thresholds matter. Under Revenue and Taxation Code section 6471, a filer whose estimated tax liability averages $17,000 or more per month is placed on the quarterly prepayment basis after CDTFA notifies the filer. Separately, EFT is required when average monthly sales tax payments over a 12-month period are $10,000 or more, or $20,000 or more for special tax and fee programs.
If the client's monthly payments average $10,000 or more, set up EFT before the next due date. If the account shows Quarterly Prepay, put each prepayment on the calendar as its own item, separate from the quarterly return.
The CDTFA-531 is not the sales tax return
A common mistake is to treat the CDTFA-531 as the return. The title on CDTFA's form PDF reads "CDTFA-531, Schedule B- Detailed Allocation by County of Sales and Use Tax Transaction". That is a county allocation schedule. Use it only when sales must be split across counties.
File from the return the client's online account shows for each period. The account version carries the period, the due date and the amount CDTFA will apply the payment to.
Due dates for the 2026 periods
CDTFA publishes these dates as month and day rules that repeat each year. The dates still open this month are the October prepayment, due November 24, 2026, and the November prepayment, due December 24, 2026. The return for the period ending December 31, 2026 is due January 31, 2027.
Quarterly Prepay filers have these dates. January prepayment February 24, February prepayment March 24, quarterly return April 30. April prepayment May 24, May 1 through June 15 prepayment June 24, quarterly return July 31. July prepayment August 24, August prepayment September 24, quarterly return October 31. October prepayment November 24, November prepayment December 24, quarterly return January 31.
Quarterly filers without prepayments file on April 30, July 31, October 31 and January 31. Monthly filers file by the end of the month after the period, so the June period is due July 31. Yearly accounts are due January 31 for the calendar year, except qualified purchasers and consumer use tax accounts, which are due April 15.
January 31, 2027 is a Sunday. CDTFA's page says that when a due date falls on a Saturday, Sunday or state holiday, the return and payment are considered on time if filed and paid the next business day. For this date that is Monday, February 1, 2027.
Prepayments: the amounts and the penalty
A Quarterly Prepay filer makes prepayments for the first two months of each quarter: January and February, April and May 1 through June 15, July and August, and October and November. CDTFA's make-a-prepayment page says each prepayment must be at least 90 percent of the state and local tax liability for the period. A second-quarter filer may pay 135 percent of May's liability instead.
The page names state and local tax for the 90 percent test and does not mention district tax. Confirm with the account how the district layer is treated for that client before setting the prepayment amount.
The penalty for each prepayment not received is 6 percent based on 90 percent of the tax liability. Taken together, that is 5.4 percent of the period's liability for each missed prepayment. On a quarter with $1 of liability, a missed prepayment costs 5.4 cents, so a client who misses both prepayments in a quarter pays about 10.8 percent of that quarter's liability in prepayment penalties.
Pay each prepayment on its own date, even when the quarterly return is not ready. A late return does not move the prepayment deadline.
Penalties for late returns and late payments
CDTFA's trouble-paying page sets a 10 percent penalty when the return is not filed by its due date and a 10 percent penalty when the tax payment is late. Interest begins accruing as soon as a payment is late, so each day of delay adds interest on top of the penalty.
When the return and the payment are both late, the combined penalty will not exceed 10 percent of the tax due for the reporting period. Without the cap, two separate 10 percent penalties would total 20 percent of the tax due. Interest still runs on the unpaid tax, so the cap limits the penalty, not the interest.
The page sets a different minimum for alcoholic beverage and timber yield accounts. If both the return and the payment are late, a 10 percent or $100 penalty, whichever is greater, applies. Check the account type before applying the 10 percent rule alone.
Payment plans are on the same online services site. The page requires that the billed amount be past due, that all required returns be filed, and that the client have the bank account number, the Statement of Account or Payment Voucher and an online services login. File the missing returns first, because a plan requires all returns to be filed.
File online and pay on time
CDTFA's file-a-return page says to file online by logging in to the secure site with a username and password, then start with the "File your return now" button. Amended returns go through the "Amend A Return" link.
CDTFA's July 8, 2026 news release (NR 26-05) announced Quick File and the Return Filing Tool for eligible retailers who file online. Quick File checks eligibility with five questions and is described as a way to complete a fiscal-yearly or annual return in under two minutes. The release does not say either tool replaces a monthly or quarterly return, so those accounts still file the regular return.
The payment methods are a direct bank account, a credit card, EFT, or a check or money order mailed to PO Box 942879, Sacramento, CA 94279-7072. The credit card processor charges a 2.3 percent service fee. A card payment must be completed before midnight Pacific time on the due date. ACH debit and third-party payments must be completed by 3:00 p.m. Pacific time.
The usual failure is an ACH payment scheduled after 3:00 p.m. Pacific time on the due date. The return can be filed on time while the payment is late, which brings the 10 percent payment penalty and interest. Ask the client to pay before the cutoff for the method, and keep the confirmation with the return.
A return is required even when there are no sales. CDTFA's page says a filing is required on or before the due date even if there are no sales to report, and that a zero payment is not needed when no tax is due.
The district layer is the one that gets missed
California's statewide base rate is 7.25 percent. The combined rate adds the district tax to that base. CDTFA's tax rate FAQ says district rates for these districts may range from 0.10 percent to 2.00 percent per district. Because the rate is set district by district, a rate taken from the city name alone can miss a district layer.
Use the Find a Sales and Use Tax Rate lookup on CDTFA's site, entering the address where the sales occur, and take the combined rate for the period. CDTFA points to Publication 44, District Taxes (Sales and Use Taxes), for the district detail.
The failure mode is a client with a warehouse in one district that ships into another, reporting every sale at the warehouse rate. Build a location list with the district for each address, and reconcile the district tax on the return to that list before the period closes.