How to Fill Out California Form CDTFA-401-A (w/Examples) + FAQs

California Form CDTFA-401-A is the State, Local, and District Sales and Use Tax Return that every retailer, wholesaler, restaurant, service business, and online seller with a California seller’s permit must file with the California Department of Tax and Fee Administration. The return reports gross sales, taxable sales, district tax by jurisdiction, and any use tax owed on out-of-state purchases. Filing it correctly keeps your seller’s permit in good standing and shields you from a 10% late penalty plus interest under R&TC §6591.

The CDTFA processes more than 1.6 million sales and use tax returns each year, and audit data published in the agency’s Annual Report shows that roughly 1 in 5 returns contains a district tax allocation error on Schedule A. That single mistake is the leading cause of CDTFA notices and back-tax assessments for small businesses.

Here is what you will learn in this guide:

• 📋 Exactly what each line, box, and schedule on CDTFA-401-A asks for and how to fill it
• 🧾 How to allocate district tax on Schedule A so you do not trigger a CDTFA audit letter
• 🍽️ Three full walkthroughs covering a clothing store, a restaurant, and a multi-location e-commerce seller
• ⏰ Filing deadlines, prepayment rules, and how to avoid the 10% late penalty
• ❓ The 12 most common filer questions answered in plain English

What the Form Is and Who Must File It

CDTFA-401-A is the long-form sales and use tax return California uses to collect the 7.25% statewide base rate plus any local and district add-on rates that push combined rates as high as 10.75% in some cities. The return is required by R&TC §6452, which directs every person holding a seller’s permit to file a return for each reporting period, even when no sales occurred. A “zero return” still must be filed, and skipping it is treated the same as filing late.

You must file CDTFA-401-A if you hold a California seller’s permit and your business sells tangible personal property, taxable services like fabrication labor, or makes out-of-state purchases used in California that were not taxed at the point of sale. Common filers include retail stores, restaurants, contractors who sell materials, online sellers shipping into California, auto dealers, and service businesses that occasionally sell parts or supplies. Wholesalers file too, even when most sales are tax-exempt resales, because the form is also where resale claims are documented.

The form interacts with several other CDTFA filings. The shorter CDTFA-401-EZ is available only to filers with no district tax to report, which is rare in California. CDTFA-531 (Schedule B) handles local tax allocation by jurisdiction, and CDTFA-531-A2 (Schedule A) handles district tax. The Schedule G attaches for diesel and motor fuel sellers, and CDTFA-1150 covers prepayment vouchers. Always confirm you have the latest revision printed at the bottom of the PDF before filing, because CDTFA updates the form whenever the Legislature changes a rate or adds a district.

Before You Start: Documents and Information You Need

Filing CDTFA-401-A goes faster and produces fewer errors when you gather every record before you log in to the CDTFA Online Services portal. The agency’s Publication 73 lists the underlying recordkeeping rules, which require retailers to keep books, sales invoices, resale certificates, and bank statements for at least four years. Auditors trace your reported numbers back to those records, so any line you cannot support is a line you may have to pay tax on later.

Use this pre-filing checklist before you start typing into the return:

• Your eight-digit CDTFA account number, because the system rejects logins that do not match your seller’s permit on file
• Total gross sales for the reporting period from your point-of-sale system or accounting software, because Line 1 starts with this figure
• A breakdown of nontaxable sales such as resales, exempt food, and labor, because Line 2’s subtractions feed into your taxable base
• Resale certificates (CDTFA-230) on file for every wholesale customer, because missing certificates convert exempt sales back into taxable sales during audit
• A district-by-district sales report tagged by ZIP code or city, because Schedule A requires you to allocate every taxable dollar to the correct district
• Records of out-of-state purchases used in California, because Line 2 of the use tax section captures this and skipping it is the most common audit finding
• Any prepayment confirmation numbers from prior CDTFA-1150 vouchers, because Line 16 credits those payments against your final liability
• Bad debt write-off journal entries, because Line 10b deductions must tie to specific invoices already reported in a prior period
• Your filing frequency assignment letter from CDTFA, because monthly, quarterly, quarterly prepay, and annual filers each have different deadlines
• Bank account routing and account numbers if paying by ACH debit, because the portal will not save partial payments

Missing any one of these items can stall your filing or force you to amend later. Amending a CDTFA return requires filing CDTFA-101 (Claim for Refund) or a corrected return, and the agency only refunds overpayments claimed within three years under R&TC §6902.

Where to Get the Form and How to Access It

The official PDF lives on the CDTFA Forms and Publications page, where you can download CDTFA-401-A along with every supporting schedule. The PDF is fillable, but CDTFA does not accept it by mail except in narrow circumstances such as a granted hardship waiver under Regulation 1707. Most filers complete the return inside the CDTFA Online Services portal, which mirrors the PDF line numbers exactly.

To access the portal, you create a username tied to your email and link it to your seller’s permit using the eight-digit CDTFA account number and a security code mailed to your business address. The first login also asks for the most recent payment amount or a recent return figure, which acts as identity proof. Once linked, the system remembers your filing frequency, your registered business locations, and your district tax footprint, and it auto-populates several lines.

Paper filing is allowed only for filers who request and receive a hardship waiver, and the mailing address is California Department of Tax and Fee Administration, PO Box 942879, Sacramento, CA 94279-7072. Walk-in filing is available at any CDTFA field office, but staff still enter the data into the same online system. The fax channel is closed for returns, although it remains open for some correspondence and waiver requests under the CDTFA contact directory.

Step-by-Step: How to Fill Out CDTFA-401-A Line by Line

The return is organized into a header block, a sales and use tax computation section (Lines 1 through 21), and several attached schedules. Work top to bottom and finish each schedule before returning to the main page, because totals from Schedule A and Schedule B flow back into Lines 13 and 14. The line-by-line walkthrough below uses the exact box numbers printed on the current revision of the form.

Header: Account Number and Reporting Period

The header asks for your CDTFA account number, your business name, your reporting period start and end dates, and the due date.

Enter the eight-digit account number printed on your seller’s permit, followed by your business’s legal name exactly as it appears on the permit, then the period covered by the return in MM/DD/YYYY to MM/DD/YYYY format. For example, Maria Lopez, owner of Lopez Boutique LLC, enters 100-123456, Lopez Boutique LLC, 04/01/2026 to 06/30/2026 for her Q2 2026 return.

A common nuance involves DBAs. If your “doing business as” name differs from the legal entity, the legal name belongs in the header and the DBA appears in your CDTFA account profile, not on the return.

A frequent mistake is entering the wrong reporting period when filing late, because the portal defaults to the next open period. Filing a Q1 return under the Q2 period creates a phantom Q1 delinquency and a 10% penalty notice. The misconception is that “the dates do not really matter because CDTFA knows what I owe,” which is wrong because the dates anchor every penalty and interest calculation.

Line 1: Total (Gross) Sales

Line 1 asks for every dollar of gross receipts from your business during the period, including taxable, nontaxable, and exempt sales.

Pull this number from your point-of-sale system’s gross sales report, then add cash sales, credit sales, and any sales you delivered but have not yet collected on, because California uses the accrual method by default under Regulation 1654. For example, Carlos, who runs Carlos Tacos in San Diego, enters 412,500 on Line 1 for Q2 2026 because his Square report shows that figure across food, drinks, and merchandise.

The nuance here is shipping and handling. If you separately state shipping and use a common carrier, those charges are excluded from Line 1, but if you bill “shipping and handling” as a combined fee, the entire amount belongs in gross sales.

The most common mistake on Line 1 is reporting net sales after refunds, which double-counts the refunds when you also deduct them on Line 5. The consequence is an understated tax liability that auditors flag the moment they reconcile your federal Schedule C against your CDTFA returns. The misconception is that “gross means after returns,” which is wrong because gross means before any deduction.

Line 2: Purchases Subject to Use Tax

Line 2 captures the cost of items you bought from out-of-state vendors without paying California tax and then used in your business.

Add the invoice cost of every taxable item you bought without sales tax, including office supplies from out-of-state online sellers, equipment imported from another state, and materials drop-shipped from outside California. For example, Janet, owner of an Oakland design studio, enters 4,800 on Line 2 because she bought a Wacom display from a New York reseller that did not charge California tax.

The nuance is that purchases for resale are excluded from Line 2 because they are not used in the business, even when the supplier did not charge tax.

The common mistake is leaving Line 2 blank because the filer assumes the out-of-state vendor “should have charged tax.” The consequence is a use tax assessment plus interest going back up to eight years if the omission is deemed substantial under R&TC §6487. The misconception is that use tax is optional, when in fact it is a self-assessed counterpart to sales tax under R&TC §6201.

Line 3: Total (Add Lines 1 and 2)

Line 3 sums Line 1 and Line 2 to produce the gross base before deductions.

Add the two figures and enter the result. Carlos enters 412,500 + 0 = 412,500 because his restaurant did not buy any out-of-state goods this quarter. The portal calculates this automatically once the prior two lines are filled.

The nuance is that if you file on paper, an arithmetic error here cascades through every later line. The mistake is rounding inconsistently, which creates a one-dollar mismatch that the portal flags. The misconception is that Line 3 is your taxable amount, but it is only the gross base.

Lines 4 through 10: Deductions

The deduction block lets you subtract sales that are not taxable, including sales for resale (Line 4), nontaxable sales of food products (Line 5), nontaxable labor (Line 6), sales to the U.S. government (Line 7), sales in interstate commerce (Line 8), bad debts (Line 10b), and other exempt sales (Line 10c).

Enter the dollar amount for each category that applies, supported by source documents like resale certificates, exemption certificates, or shipping records. For example, Lopez Boutique enters 18,400 on Line 4 for resales to a stylist who provided a valid CDTFA-230, and 0 on Line 5 because clothing is not exempt food.

The nuance is that food products are exempt only when sold for human consumption off-premises, so a restaurant selling hot prepared food cannot use Line 5, but a grocery store selling cold sandwiches can.

The mistake filers make most often is claiming bad debt on Line 10b without first reporting the sale and paying tax in a prior period, which violates Regulation 1642. The consequence is a denied deduction and a recapture assessment. The misconception is that any uncollected invoice qualifies, when in fact only fully written-off accounts that were previously taxed and reported can be deducted.

Line 11: Total Nontaxable Transactions

Line 11 sums every deduction from Lines 4 through 10c.

Add each line and enter the total. The portal does this automatically. Maria’s total deductions of 22,300 appear on Line 11 once she finishes the deduction block.

The nuance is that any deduction missing supporting documentation is at risk during audit, even when the math is correct. The mistake is double-counting an exempt sale in two different deduction categories. The misconception is that Line 11 is a “soft” number, when in fact it is the most heavily scrutinized figure on the return.

Line 12: Transactions Subject to State Tax

Line 12 subtracts Line 11 from Line 3 to produce your statewide taxable base.

The portal calculates this automatically. Carlos’s Line 12 reads 388,000 after subtracting his 24,500 in resales and exempt cold-food sales from his 412,500 gross.

The nuance is that Line 12 is the figure that drives the 7.25% state and local base tax, so an error here multiplies through every later line. The mistake is forcing a number on Line 12 that does not equal Line 3 minus Line 11. The misconception is that Line 12 already includes district tax, when district tax is calculated separately on Schedule A.

Line 13: State Tax (6.00% rate)

Line 13 multiplies Line 12 by 0.0600 to compute the state’s share of the base sales tax.

The portal does the math, but you should verify it. Carlos sees 388,000 × 0.0600 = 23,280 on Line 13.

The nuance is that the 6.00% is the pure state portion under R&TC §6051, and the remaining 1.25% of the 7.25% base is split between county and city per R&TC §7202. The mistake is changing the rate manually when a rate change is announced mid-period; you must instead split the period into two returns or follow the agency’s transition guidance. The misconception is that this is the “total tax,” when it is only one slice.

Line 14: County, Local, and District Tax

Line 14 captures the 1.25% Bradley-Burns local tax allocated through Schedule B and the district tax allocated through Schedule A.

Complete Schedule B by allocating Line 12 across the cities and counties where the sales occurred, then complete Schedule A for any district add-on tax. Maria allocates her entire 388,000 to Los Angeles County for Schedule B and to the Los Angeles County district (LACMTA) at 2.25% on Schedule A.

The nuance is that out-of-state shippers must allocate based on the destination of the goods, not the seller’s location, under Regulation 1802. The mistake is allocating all sales to your storefront’s city when you ship statewide, which understates district tax owed in higher-rate cities. The misconception is that “district tax does not apply if I am outside the district,” which is wrong for sellers engaged in business in the district under the post-Wayfair economic nexus rules in R&TC §7262.

Line 15: Total State, Local, and District Tax

Line 15 adds Lines 13 and 14 to produce gross tax before credits.

The portal calculates this automatically. Carlos sees Line 15 as 23,280 state + 17,460 local and district = 40,740.

The nuance is that Line 15 does not yet include penalties or interest, which appear on Lines 19 and 20. The mistake is treating Line 15 as the amount to remit, then forgetting to subtract prepayments. The misconception is that this is the “final number,” but it is only the pre-credit subtotal.

Line 16: Less Tax Prepayments

Line 16 credits any prepayments you made during the period using CDTFA-1150.

Enter the total of every prepayment voucher posted to your account during the period. A quarterly-prepay filer like Aisha’s e-commerce store enters 12,000 on Line 16 because she made two 6,000 prepayments in the first two months of the quarter.

The nuance is that quarterly prepay filers must make prepayments equal to at least 90% of each month’s actual liability or face a 6% penalty under R&TC §6476. The mistake is entering the wrong prepayment amount; the portal cross-checks against payments on file. The misconception is that prepayments are optional for quarterly prepay filers, when they are mandatory.

Line 17: Remaining Tax

Line 17 subtracts Line 16 from Line 15.

Aisha’s Line 17 is 40,740 minus 12,000 = 28,740. The portal calculates this automatically.

The nuance is that a negative number on Line 17 means you overpaid and should consider filing CDTFA-101 for a refund. The mistake is leaving a credit balance on the account instead of claiming it, which can be lost after the three-year statute. The misconception is that overpayments automatically refund, when they do not without a claim.

Lines 18 through 21: Penalty, Interest, and Total Amount Due

Line 18 is reserved for special credits, Line 19 is the 10% late penalty, Line 20 is interest computed using the CDTFA interest rate page, and Line 21 is the total amount due.

If you are filing late, calculate penalty as Line 17 × 0.10 and interest as Line 17 × the monthly rate × months late, then enter the total on Line 21. Marcus, who files Q2 2026 a month late, calculates 28,740 × 0.10 = 2,874 penalty and roughly 144 in interest, producing a Line 21 of 31,758.

The nuance is that the penalty can be waived by filing CDTFA-735 and showing reasonable cause under R&TC §6592. The mistake is paying tax but not penalty, which leaves the penalty accruing additional interest. The misconception is that “I will fix it next quarter” works, when penalties attach the day after the due date.

Schedule A: District Tax Allocation

Schedule A is where you list every district where you made taxable sales and the corresponding taxable amount.

For each district, enter the district code, the taxable sales delivered into that district, and the district rate, then let the portal compute the district tax. Aisha’s e-commerce store sells into Los Angeles County (LACMTA, 2.25%), San Francisco County (1.25%), and Alameda County (3.00% combined), so each line of Schedule A captures the taxable amount and rate per district.

The nuance is that you can look up the correct district rate using the CDTFA Tax Rate by Address tool, which maps every California address to its current combined rate. The mistake filers make most often is allocating all sales to a single home district to save time, which is the leading cause of CDTFA notices. The misconception is that “Schedule A is optional if I do not collect district tax,” when the obligation to remit follows the sale, not the collection.

Schedule B: Local Tax Allocation

Schedule B allocates the 1.00% local Bradley-Burns share to the city or unincorporated county where the sale was negotiated.

For each location, enter the jurisdiction code and the taxable amount sold. Carlos enters his entire taxable base under San Diego because every plate of food was sold and consumed at his restaurant.

The nuance is that delivery sales are sourced under Regulation 1802, which generally sources to the place of negotiation rather than delivery. The mistake is allocating to the buyer’s address, which produces an under-allocation to your home city and triggers a Bradley-Burns reallocation audit. The misconception is that Schedule B and Schedule A use the same sourcing rules, when in fact they differ.

Three Filled-Out Examples Using Real Scenarios

The three scenarios below show how very different California businesses complete the same return. Each table walks one named filer through the most important sections of CDTFA-401-A.

Scenario 1: Maria Lopez, Single-Location Clothing Store in Los Angeles

Form Section	What Maria Enters
Header — Account & Period	100-123456, Lopez Boutique LLC, 04/01/2026 to 06/30/2026
Line 1 — Total Gross Sales	180,000
Line 2 — Use Tax Purchases	1,200 (display fixtures from Nevada)
Line 4 — Sales for Resale	18,400 (stylist resale account)
Line 11 — Total Deductions	18,400
Line 12 — Taxable Transactions	162,800
Schedule A — District Allocation	162,800 to LACMTA at 2.25%
Schedule B — Local Allocation	162,800 to City of Los Angeles
Line 15 — Total Tax	15,673
Line 21 — Amount Due	15,673

Scenario 2: Carlos Ruiz, Restaurant in San Diego

Form Section	What Carlos Enters
Header — Account & Period	100-456789, Carlos Tacos Inc., 04/01/2026 to 06/30/2026
Line 1 — Total Gross Sales	412,500
Line 2 — Use Tax Purchases	0
Line 5 — Exempt Food Products	24,500 (cold packaged retail items)
Line 11 — Total Deductions	24,500
Line 12 — Taxable Transactions	388,000
Schedule A — District Allocation	388,000 to San Diego County TransNet at 0.50% plus city add-ons
Schedule B — Local Allocation	388,000 to City of San Diego
Line 15 — Total Tax	31,234
Line 21 — Amount Due	31,234

Scenario 3: Aisha Patel, Multi-Location E-Commerce Seller

Form Section	What Aisha Enters
Header — Account & Period	100-789012, Patel Goods LLC, 04/01/2026 to 06/30/2026
Line 1 — Total Gross Sales	620,000
Line 2 — Use Tax Purchases	7,800 (packaging from Texas)
Line 4 — Sales for Resale	45,000
Line 8 — Interstate Commerce Sales	180,000 (shipped outside CA)
Line 12 — Taxable Transactions	402,800
Schedule A — District Allocation	Allocated across LA, SF, Alameda, and Santa Clara districts
Line 16 — Tax Prepayments	12,000
Line 17 — Remaining Tax	24,500
Line 21 — Amount Due	24,500

How to File the Completed Form

The default filing channel is the CDTFA Online Services portal, which accepts the return and payment in one session. Log in, choose the open reporting period, complete the return on screen, and select a payment option. ACH debit is free, credit card payments carry a 2.3% service fee charged by the third-party processor, and ACH credit (push) is free but requires you to initiate the transfer through your bank using the routing details on the CDTFA payment options page. Processing time is immediate; you receive a confirmation number to print or save.

Paper filing is allowed only after CDTFA grants a hardship waiver. The mailing address is California Department of Tax and Fee Administration, PO Box 942879, Sacramento, CA 94279-7072, and a check made payable to “California Department of Tax and Fee Administration” must be enclosed with the voucher. Postmarked-by-the-due-date counts as timely under Regulation 1702, and your proof of filing is the certified mail return receipt.

In-person filing is available at any CDTFA field office during business hours. Bring a printed copy of the completed return and a check, money order, or cashier’s check; cash is accepted but not recommended. Office staff date-stamp your copy on the spot, and that stamped copy is your proof of filing. Fax filing is not accepted for returns. Expect online returns to post within 24 hours, paper returns within 10 to 15 business days, and in-person returns same-day.

What Happens After You File

After you submit, CDTFA posts the return to your account and matches the payment. The system issues a confirmation number, and you can log back in to the portal to view return history, payment history, and any open balances. Most filings clear without further action.

If your return triggers a system flag, such as Schedule A allocations that diverge sharply from the prior period or a use tax line that seems out of pattern, CDTFA may issue a Notice of Determination under R&TC §6481 or open a desk audit. You have 30 days to petition for redetermination using CDTFA-416. Missing the 30-day window converts the notice into a final assessment.

If you discover a mistake after filing, file an amended return through the same portal using the “amend a return” function, or submit CDTFA-101 if you overpaid. Refund claims must be filed within three years of the original due date under R&TC §6902. CDTFA typically resolves refund claims within 90 days, though complex claims may take longer.

Mistakes to Avoid When Filling Out the Form

Sales tax returns reward precision. The following errors generate the most CDTFA notices and assessments each year, and each one is preventable.

• Allocating all sales to your home district on Schedule A, which causes under-reporting in higher-rate districts and triggers a CDTFA reallocation audit
• Reporting net sales on Line 1 instead of gross sales, which double-counts your refund deduction and understates the base
• Leaving Line 2 blank when you have made out-of-state purchases, which leads to a use tax assessment plus eight years of lookback under R&TC §6487
• Claiming a resale deduction without a valid resale certificate on file, which converts the sale back to taxable during audit
• Deducting bad debts that were never reported as taxable in a prior period, which violates Regulation 1642 and is recaptured
• Treating combined “shipping and handling” as exempt, which is wrong because the handling portion is taxable
• Using the wrong reporting period, which the portal defaults to the next open period and creates a phantom delinquency
• Forgetting to include district tax for delivery sales into out-of-district areas, which is the post-Wayfair economic nexus rule
• Paying the tax but skipping the penalty calculation on Line 19, which leaves penalty accruing additional interest
• Missing a quarterly prepayment, which triggers a 6% penalty under R&TC §6476
• Mismatching legal name and DBA in the header, which can delay processing and refund posting
• Rounding inconsistently between Line 1, the schedules, and the totals, which the portal flags and refuses to submit

Do’s and Don’ts

A short list of habits separates clean filers from filers who attract notices.

• Do reconcile Line 1 to your federal Schedule C or corporate income tax return, because CDTFA cross-matches with the FTB
• Do save every confirmation number and PDF copy, because CDTFA’s portal history can lag and your records are the tiebreaker
• Do use the Tax Rate by Address tool for every delivery ZIP, because rates change frequently
• Do file even a zero return, because non-filing penalties are steeper than late penalties
• Do request penalty relief on CDTFA-735 when you have reasonable cause, because the agency grants it more often than filers expect

• Do keep four years of records under Publication 73, because that is the statutory audit window

• Don’t guess at district allocations, because guesses become the basis for assessments

• Don’t claim a deduction you cannot document, because undocumented deductions are presumed taxable
• Don’t pay tax personally from a sole-prop bank account when filing under an LLC, because mismatched payors create posting errors
• Don’t ignore CDTFA notices, because the 30-day petition window is strict
• Don’t amend a return without first reading Publication 17, because amendments can re-open closed periods
• Don’t co-mingle sales tax collected with operating cash, because under R&TC §6051.2 sales tax is held in trust

Pros and Cons of Filing on Your Own vs. With Help

Many small business owners file CDTFA-401-A themselves, while others hire a CPA or sales tax specialist. Each route has tradeoffs.

Pros of filing on your own:

• Saves the 200 to 600 dollars per return that a CPA typically charges
• Builds direct knowledge of your sales mix and district footprint
• Lets you file at the last minute without coordinating with an outside professional
• The CDTFA Online Services portal is well documented with line-level help
• Free CDTFA tax help webinars are offered through the CDTFA Tax Education page

Cons of filing on your own:

• District tax allocation is technical and the leading source of audit findings
• Use tax on out-of-state purchases is easy to miss
• Penalty relief paperwork requires familiarity with R&TC §6592 standards
• Audits compound errors across multiple periods, multiplying exposure
• Time spent filing is time away from running the business

FAQs

Do I have to file CDTFA-401-A if I had no sales this period?

Yes. California requires every active seller’s permit holder to file even a zero return, and skipping a zero return triggers a non-filing penalty and possible permit suspension under R&TC §6452.

Can I file CDTFA-401-A on paper?

No. CDTFA requires online filing through its portal, and paper filing is allowed only with a granted hardship waiver under Regulation 1707.

Do I write my legal name or DBA in the header?

Yes, write the legal entity name that matches your seller’s permit, and keep the DBA in your account profile only, because mismatches delay processing and refund posting.

Should Line 1 include sales tax I collected?

No. Line 1 is gross sales excluding the tax collected, because including tax in Line 1 inflates the base and overstates your liability on Line 13.

Do I report exempt food on Line 5 if I run a restaurant?

No, hot prepared restaurant food is taxable, so most restaurants report 0 on Line 5 and only grocery-style cold packaged items qualify under Regulation 1603.

Do shipping charges count as taxable sales on Line 1?

Yes, when shipping is bundled with handling or you do not use a common carrier, but separately stated shipping by common carrier is excluded under Regulation 1628.

Can I deduct uncollected invoices on Line 10b?

Yes, but only when the invoice was previously reported as taxable, the debt is fully written off for income tax purposes, and the deduction follows Regulation 1642.

Do I owe district tax on sales shipped to other California cities?

Yes, post-Wayfair economic nexus under R&TC §7262 requires retailers to collect and remit district tax on deliveries throughout California once thresholds are met.

Can CDTFA waive the 10% late penalty?

Yes, by filing CDTFA-735 and showing reasonable cause such as serious illness, natural disaster, or first-time filer error under R&TC §6592.

Do quarterly prepay filers still file CDTFA-401-A?

Yes, prepayments are made on CDTFA-1150 vouchers, and the full quarterly return is still due on CDTFA-401-A, with prepayments credited on Line 16.

Should I list every district on Schedule A even when sales were small?

Yes, every district where you delivered taxable sales must appear with the actual taxable amount, because rolling small districts into a larger one is the most common Schedule A error.

Can I amend a CDTFA-401-A after filing?

Yes, through the CDTFA Online Services portal using the amend function, and refund claims must be filed within three years under R&TC §6902.

Do I need to attach Schedule B if I only have one location?

Yes, Schedule B is required whenever the return reports any taxable transactions, because the 1.00% Bradley-Burns share must be allocated to a specific city or unincorporated county under R&TC §7202.