California Form FTB 3538 is the Payment for Automatic Extension for LPs, LLPs, and REMICs voucher that limited partnerships, limited liability partnerships, and real estate mortgage investment conduits use to send the California Franchise Tax Board (FTB) any tax owed when they take the automatic 7-month extension to file Form 565 or Form 568. The voucher itself does not request the extension — California grants the extension automatically — but it must travel with the payment if the entity owes the $800 annual tax, the LLC or LLP fee, or any other balance by the original due date.
The extension is automatic, but the payment is not. The FTB receives more than 200,000 partnership returns each year, and a large share of late-payment penalties on those returns trace back to a missed or mis-coded FTB 3538 voucher, according to the agency’s published tax gap and compliance data.
Here is what this guide covers:
- 📌 What Form FTB 3538 is, who must file it, and the exact 2025 revision you should use
- 🗓️ The original due date, the 7-month automatic extension, and the penalty math when payment is late
- ✍️ A line-by-line walkthrough of every box on the voucher, with sample entries
- 🧾 Three full filled-out examples for an LP, an LLP, and a REMIC
- 💸 How to pay through Web Pay, mail, or credit card, plus what to keep as proof
What Form FTB 3538 Is and Who Must File It
Form FTB 3538 is a one-page payment voucher issued by the California Franchise Tax Board for entities that file Form 565 (Partnership Return of Income) or Form 568 (Limited Liability Company Return of Income, used by LLPs and some REMICs). The voucher exists because California grants every partnership and REMIC an automatic 7-month filing extension under R&TC §18567, but the underlying tax is still due on the original return date.
Three entity types use this voucher. Limited partnerships (LPs) registered with the California Secretary of State owe the $800 annual tax under R&TC §17935. Limited liability partnerships (LLPs), typically law and accounting firms, owe the same $800 under R&TC §17948. Real estate mortgage investment conduits (REMICs) that file Form 565 also use FTB 3538 when they have any California tax liability.
An entity does not file FTB 3538 if it owes nothing, paid the full balance through Web Pay, or is in its first taxable year and qualifies for the first-year exemption added by AB 85 (2020). LLCs taxed as corporations use Form FTB 3539 instead, and single-member LLCs treated as disregarded entities still owe the $800 and may need FTB 3538 attached to their Form 568. The 2025 revision (used for taxable years beginning in 2025 and filed in 2026) carries a revision date of (REV 2025) in the lower-left corner of the form, which is the version this article walks through.
Before You Start: Documents and Information You Need
Gather everything before you open the voucher. The fields are short, but each one is cross-checked against the FTB’s BETS database, and a typo on the entity ID or a wrong tax year will route the payment to the wrong account. Once a payment lands in the wrong year, getting it moved requires a written request to the FTB Business e-file Help Desk and can take 60 to 90 days.
The pre-filing checklist below covers every item the partnership or REMIC needs in hand before completing FTB 3538.
- California Secretary of State (SOS) file number — A 12-digit number for LPs (starting with 200 through 202) and a 7-digit number for LLPs/LLCs. Without it, the FTB cannot match the payment to the correct entity, and the $800 stays unposted.
- Federal Employer Identification Number (FEIN) — A 9-digit IRS-issued number. The FTB uses this as a backup match when the SOS file number is wrong.
- Exact legal entity name — Must match the name on the SOS registration. Smith & Lopez LLP is not the same record as Smith and Lopez, LLP.
- California mailing address — The address of record with the SOS or the FTB. Notices about the payment go here.
- Taxable year beginning and ending dates — Calendar-year filers use 01/01/2025 and 12/31/2025. Fiscal-year filers must enter their actual short-year dates.
- Total tax liability estimate — A reasonable estimate of the $800 annual tax plus the LLC fee (for Form 568 filers) or any apportioned tax.
- Prior payments already made — Any estimated tax, prior-year overpayment credit, or Form 3522 annual tax voucher already submitted.
- Bank account or credit card information — Routing and account number for Web Pay, or a Visa, MasterCard, Discover, or American Express card for ACI Payments.
Having a copy of last year’s filed Form 565 or 568 nearby helps too. The amounts in Box 1 of FTB 3538 should be a reasonable estimate based on prior-year activity, and the FTB compares this to actual liability when the return is filed.
Where to Get the Form and How to Access It
The current voucher lives on the FTB’s forms search page under form number 3538. Always pull the version that matches the taxable year on your return — using a 2024 voucher to pay 2025 tax will cause the payment to post to the wrong year. The form is published as a fillable PDF, so you can type directly into the boxes, save the file, and print it for mailing.
The FTB also mails pre-printed FTB 3538 vouchers each January to every active LP, LLP, and REMIC on file. The pre-printed version is identical in content but already has the entity’s name, address, SOS number, and FEIN encoded in the scan line at the bottom. If you receive a pre-printed voucher, use it — the encoded scan line speeds posting by roughly two weeks compared with a hand-completed blank.
Tax software vendors such as CCH Axcess, Lacerte, ProSeries, and Drake generate FTB 3538 automatically as part of their California partnership module. Software-generated vouchers are accepted by the FTB as long as the scan line at the bottom prints clearly and the form retains the FTB’s substitute-form approval code.
If you cannot print, the FTB’s Tax Forms Request Unit will mail a paper copy free of charge within 10 business days. Calling 1-800-338-0505 and selecting the business form option also triggers a mailed copy.
Step-by-Step: How to Fill Out Form FTB 3538 Line by Line
The voucher has only seven data fields plus a payment box, but each one carries weight. Work top to bottom in the order printed, using black or dark-blue ink if completing by hand. Do not staple the check to the voucher — the FTB’s high-speed scanners reject stapled documents and route them to manual processing, which delays posting by up to 30 days, according to the agency’s payment processing guidance.
Field 1: Taxable Year Beginning and Ending Dates
What it asks in plain English. This is the start and end date of the tax year you are paying for, not the year you are paying in. Calendar-year filers will write 01/01/2025 and 12/31/2025 on a 2025 voucher.
How to answer it. Enter the dates in MM/DD/YYYY format. Use leading zeros for single-digit months and days. Do not write 2025 alone, and do not abbreviate the year as 25.
Example. Pacific Coast Vineyards, LP is a calendar-year filer, so its general partner enters 01/01/2025 in the beginning box and 12/31/2025 in the ending box.
Nuance. Fiscal-year and short-year filers must enter the actual short-period dates. A partnership that elected a March 31 year end writes 04/01/2025 and 03/31/2026, and uses the 2025 voucher because that is the year the period began.
Common mistake and consequence. Writing the current calendar year (the year you are mailing) instead of the taxable year. The FTB posts the payment to the wrong tax year, leaving the prior year unpaid and triggering a late-payment notice plus a 5% penalty under R&TC §19132.
Misconception. Filers think the date matches the return due date. It does not — these boxes describe the tax year being paid, never the filing date.
Field 2: California Secretary of State (SOS) File Number
What it asks in plain English. This is the unique number the California Secretary of State assigned when the LP or LLP first registered.
How to answer it. LPs use a 12-digit number starting with 200, 201, or 202. LLPs use a 7-digit number that may begin with a leading zero — keep the zero. Do not enter dashes or spaces.
Example. Pacific Coast Vineyards, LP enters 201912310123. Smith & Lopez LLP enters 0312456.
Nuance. REMICs that are not registered with the California SOS leave this field blank and rely on the FEIN box only. Out-of-state LPs that registered with California still receive a California SOS number when they file their LP-5 — use that number, not the home-state number.
Common mistake and consequence. Entering the FEIN here by accident. The FTB’s matching software bounces the payment to the suspense file, where it can sit unposted for 4 to 6 weeks before staff manually reclaim it.
Misconception. Filers think this is optional if the FEIN is filled in. It is not — the SOS number is the FTB’s primary key for LPs and LLPs.
Field 3: Federal Employer Identification Number (FEIN)
What it asks in plain English. The 9-digit Employer Identification Number the IRS issued to the partnership on Form SS-4.
How to answer it. Format it as XX-XXXXXXX with the dash. The fillable PDF auto-formats; on a paper form, write the dash by hand.
Example. Pacific Coast Vineyards, LP enters 87-1234567.
Nuance. A partnership that recently merged or reorganized may have a new FEIN. Use the FEIN that appears on the current return — using the predecessor entity’s FEIN routes the payment to the closed account.
Common mistake and consequence. Transposing two digits (87-1243567 instead of 87-1234567). The payment posts to a different taxpayer’s account, and unwinding the misposting requires a Form FTB 3705 request that can take 90 days.
Misconception. Filers believe a single-member LLC can use the member’s Social Security Number here. It cannot — the FTB requires the LLC’s own FEIN on FTB 3538.
Field 4: Entity Name
What it asks in plain English. The full legal name of the LP, LLP, or REMIC as it appears on the SOS registration or IRS records.
How to answer it. Type or print the name exactly as registered, including punctuation, LP, L.P., LLP, or L.L.P. designators. Use upper-and-lower case if filling on screen; use ALL CAPS if writing by hand.
Example. Pacific Coast Vineyards, LP enters Pacific Coast Vineyards, LP — comma included.
Nuance. A doing-business-as (DBA) name does not belong here. The FTB matches on the registered name only.
Common mistake and consequence. Dropping the entity designator (writing Pacific Coast Vineyards instead of Pacific Coast Vineyards, LP). Mismatched names trigger a name-control failure, and the payment lands in the suspense file.
Misconception. Filers think small punctuation differences do not matter. They do — the FTB’s match algorithm is strict on commas, ampersands, and the LP or LLP suffix.
Field 5: Address Block (Street, City, State, ZIP)
What it asks in plain English. The mailing address of record where the FTB should send notices about this payment.
How to answer it. Use the address currently on file with the SOS or the FTB. P.O. Boxes are allowed. International addresses use the foreign country and postal code lines on the lower portion of the form.
Example. Pacific Coast Vineyards, LP enters 4421 Vineyard Hill Road, Napa, CA 94558.
Nuance. If the address differs from the FTB’s record, the agency updates its file but only after the return itself is processed — file Form FTB 3533-B for an immediate change.
Common mistake and consequence. Using the CPA’s address. Notices then route to the preparer, who may not forward them in time, and the partnership misses penalty-abatement deadlines.
Misconception. Filers assume putting a new address on the voucher counts as an official change of address. It does not — only Form 3533-B does.
Field 6: Tentative Amount of Tax (Line 1)
What it asks in plain English. Your best estimate of the entity’s total California tax for the year — the $800 annual tax, plus the LLC fee tier (Form 568 filers) or any other tax due.
How to answer it. Calculate $800 plus, for LLCs filing Form 568, the LLC fee tier based on California-source total income. Round to whole dollars.
Example. Pacific Coast Vineyards, LP enters 800 because LPs owe only the $800 annual tax. Bayshore Builders, LLC (filing Form 568 with $600,000 of California income) enters 3,300 — the $800 plus the $2,500 fee tier.
Nuance. REMICs and LLPs do not owe the LLC fee — only the $800. Partnerships that have nonresident withholding obligations should add the Form 592 amount as well.
Common mistake and consequence. Forgetting the LLC fee tier. The voucher pays only the $800, and the unpaid fee accrues 5% per month under R&TC §19132 plus interest under R&TC §19521.
Misconception. Filers think tentative means guess and adjust later for free. The estimate must be reasonable — a lowball number triggers an underpayment penalty even if the final return is on extension.
Field 7: Amount of Payment (Line 2)
What it asks in plain English. The dollar amount you are sending with this voucher today.
How to answer it. Subtract any prior payments (estimated tax, prior-year credit, Form 3522 annual tax already paid) from Line 1. Enter the difference.
Example. Pacific Coast Vineyards, LP paid the $800 with Form 3522 in April, so Line 2 is 0 and the partnership does not mail the voucher at all.
Nuance. If Line 2 is zero, do not mail the voucher — keep it in your records as proof of the calculation. If Line 2 is greater than zero, attach a check or money order made payable to Franchise Tax Board with the FEIN and 2025 FTB 3538 in the memo line.
Common mistake and consequence. Mailing a zero-balance voucher anyway. The FTB scans it as a $0 payment, but the noise can mask a later actual payment for the same year. Worse: paying twice — once via Web Pay and once by mailing a check — creates a credit balance that takes weeks to refund.
Misconception. Filers believe writing a higher amount creates a deposit toward next year. It does not — overpayments stay credited to the current year unless the return elects a credit forward on Form 565 or 568.
Three Filled-Out Examples Using Real Scenarios
Each scenario below follows one named filer through the whole voucher. Italicized text shows what the filer actually writes on the form.
Scenario 1: Pacific Coast Vineyards, LP (LP Owing Only the $800)
Maria Reyes is the general partner of Pacific Coast Vineyards, LP, a Napa-based LP with two limited partners and no employees. The partnership owes only the $800 annual tax for 2025 and already paid it on April 15 using Form 3522. She still completes FTB 3538 to document the extension calculation but does not mail it.
| Form Section | What Maria Enters |
|---|---|
| Taxable year beginning | 01/01/2025 |
| Taxable year ending | 12/31/2025 |
| California SOS file number | 201912310123 |
| FEIN | 87-1234567 |
| Entity name | Pacific Coast Vineyards, LP |
| Address | 4421 Vineyard Hill Road, Napa, CA 94558 |
| Line 1 — Tentative tax | 800 |
| Prior payments (Form 3522) | 800 |
| Line 2 — Amount of payment | 0 |
| Action taken | Voucher retained, not mailed |
Scenario 2: Smith & Lopez LLP (Law Firm Owing $800 Plus a Late Top-Up)
Daniel Lopez is the managing partner of Smith & Lopez LLP, a 14-attorney litigation firm in Los Angeles. The firm forgot to mail Form 3522 in April. Daniel files FTB 3538 in March 2026 with the full $800 to cure the miss before the October extended deadline.
| Form Section | What Daniel Enters |
|---|---|
| Taxable year beginning | 01/01/2025 |
| Taxable year ending | 12/31/2025 |
| California SOS file number | 0312456 |
| FEIN | 94-2876543 |
| Entity name | Smith & Lopez LLP |
| Address | 800 South Figueroa Street, Suite 1200, Los Angeles, CA 90017 |
| Line 1 — Tentative tax | 800 |
| Prior payments | 0 |
| Line 2 — Amount of payment | 800 |
| Payment method | Check payable to Franchise Tax Board, memo 94-2876543 2025 FTB 3538 |
Scenario 3: Sierra Mortgage Holdings REMIC (REMIC With Apportioned Tax)
Aisha Patel administers Sierra Mortgage Holdings, a REMIC that files Form 565 and has $4,200 of California tax due after apportioning servicing income to the state. The REMIC has no SOS number because it is a federal trust, so Aisha leaves Field 2 blank and uses the FEIN as the primary identifier.
| Form Section | What Aisha Enters |
|---|---|
| Taxable year beginning | 01/01/2025 |
| Taxable year ending | 12/31/2025 |
| California SOS file number | (blank) |
| FEIN | 46-5678901 |
| Entity name | Sierra Mortgage Holdings REMIC |
| Address | 2150 North Capitol Avenue, Sacramento, CA 95816 |
| Line 1 — Tentative tax | 4,200 |
| Prior payments | 0 |
| Line 2 — Amount of payment | 4,200 |
| Payment method | Web Pay ACH debit; voucher retained as backup |
How to File the Completed Form
The FTB accepts payment three ways. Each channel has its own posting timeline, fee structure, and proof-of-filing.
Online via Web Pay for Businesses. Free. Enter the FEIN, choose Extension Payment (Form 3538), and authorize an ACH debit. The system issues a confirmation number — save the screenshot. Posting is next business day, and the entity does not mail the paper voucher when paying this way.
By mail with a check or money order. No fee. Make the check payable to Franchise Tax Board and write the FEIN, taxable year, and FTB 3538 on the memo line. Mail to Franchise Tax Board, P.O. Box 942857, Sacramento, CA 94257-0531 using USPS Certified Mail with Return Receipt for proof of timely filing under the timely-mailing-as-timely-filing rule. Posting takes 10 to 15 business days.
By credit card via ACI Payments. A 2.3% convenience fee applies. Visa, MasterCard, Discover, and American Express are accepted. The vendor issues a confirmation number; posting to the FTB occurs within 2 business days.
The original due date for calendar-year LPs and LLPs is the 15th day of the 3rd month after the tax year ends — March 15, 2026 for 2025 calendar-year filers, per R&TC §18633. REMICs that file Form 565 share the same due date. The automatic 7-month extension under R&TC §18567 pushes the filing deadline to October 15, but the payment must still arrive by March 15 to avoid penalties.
What Happens After You File
For Web Pay and credit card payments, the FTB updates the entity’s account within 1 to 2 business days, and the partnership can confirm posting through MyFTB. Mailed payments take 10 to 15 business days to post; during peak season (March 1 to March 20), expect up to 25 business days.
If the payment matches or exceeds the actual liability shown on the eventual Form 565 or 568, no penalty applies, and any overage credits forward or refunds when the return is filed. If the payment falls short, the FTB assesses the late-payment penalty under R&TC §19132 at 5% of the unpaid amount plus 0.5% per month, capped at 25%, plus interest under R&TC §19521 set quarterly.
The FTB sends a Notice of Tax Return Change (Form FTB 5818) if the voucher amount does not reconcile to the filed return. Respond within 60 days through MyFTB or by mail to preserve appeal rights with the Office of Tax Appeals. Filers who disagree with a penalty can request abatement using Form FTB 2917 for one-time abatement under R&TC §19132.5.
Mistakes to Avoid When Filling Out the Form
Each error below has tripped up filers on real FTB 3538 vouchers. The consequence is what the agency actually does in response.
- Writing the calendar year instead of the taxable year. Payment posts to the wrong year and the correct year goes delinquent.
- Entering the FEIN in the SOS file number box. Voucher routes to the suspense file for 4 to 6 weeks.
- Dropping the LP or LLP suffix from the entity name. Name-control mismatch holds the payment.
- Stapling the check to the voucher. Manual processing adds 30 days to posting.
- Mailing a zero-balance voucher. Creates a phantom $0 transaction that masks later real payments.
- Paying the $800 only when the LLC fee is also due. Triggers a 5% per month penalty on the unpaid fee.
- Using the prior-year voucher. Payment posts to the wrong taxable year, exactly like the first mistake.
- Forgetting to subtract the Form 3522 prepayment. Causes a duplicate payment that takes weeks to refund.
- Mailing without Certified Mail. No proof of timely filing if the FTB later claims it arrived late.
- Paying via Web Pay and mailing the voucher. Doubles the payment and creates a credit balance refund cycle.
- Using a CPA’s address without filing Form 3533-B. Notices route away from the entity, and abatement deadlines pass unmet.
- Skipping the FEIN memo on the check. Untraceable check ends up in suspense.
Do’s and Don’ts
Do pay through Web Pay — it is free, instant, and creates a digital audit trail.
Do confirm the SOS file number on bizfile Online before writing it on the voucher.
Do keep a scanned copy of the completed voucher and the check or confirmation number for at least 4 years.
Do mail by USPS Certified Mail with Return Receipt — it is the cheapest insurance against a we never received it notice.
Do match Line 1 to a reasonable estimate based on prior-year activity to avoid underpayment penalties.
Do check MyFTB 10 business days after mailing to confirm posting.
Don’t mail a zero-balance voucher — keep it in your file instead.
Don’t staple, paper-clip, or tape the check to the voucher.
Don’t use the FEIN where the SOS number belongs, or vice versa.
Don’t wait until March 14 to mail — Certified Mail postmarks at 5 p.m. cutoffs are not always honored.
Don’t assume the extension covers the payment — California’s automatic extension covers filing only.
Don’t use a substitute voucher from a non-approved tax software without the FTB’s substitute-form code printed at the bottom.
Pros and Cons of Filing on Your Own vs. With Help
Pros of self-filing. Saves the $200 to $500 a CPA typically charges for a partnership extension. Builds in-house knowledge of the FTB’s payment systems. Gives the general partner direct access to MyFTB confirmation. Avoids the delay of routing the voucher through a third party. Lets the entity time the payment to its own cash flow.
Cons of self-filing. Easy to miss the LLC fee tier on Form 568. No built-in penalty math for late-payment abatement. Mistakes on the SOS or FEIN field can take 60 to 90 days to unwind. Calendar-year deadline pressure overlaps with personal Form 1040 deadlines. No professional shield against FTB notices.
Pros of using a CPA or EA. The preparer files FTB 3538 inside the broader extension package. Tax software auto-populates the scan line. Errors are professionally insured. The CPA monitors MyFTB for posting. Penalty abatement requests are drafted by someone who has done it before.
Cons of using a CPA or EA. Cost ranges from $200 to $500 for an LP extension and $400 to $1,000 for an LLP. Communication delays between partner and preparer. Notices go to the CPA’s address by default. Some preparers do not file FTB 3538 unless asked. Adds a hand-off point where the SOS number can be miscopied.
Web Pay vs. Mail vs. Credit Card
| Channel | Trade-Off |
|---|---|
| Web Pay (ACH) | Free, posts in 1 business day, requires a CA bank account |
| Mail (check) | Free, slow posting (10–15 days), needs Certified Mail for proof |
| Credit card (ACI) | 2.3% fee, posts in 2 days, useful when bank account is unavailable |
FAQs
Is Form FTB 3538 the same as the extension itself?
No. California grants the 7-month extension automatically under R&TC §18567. FTB 3538 is only the payment voucher that travels with any tax owed by the original due date.
Do I file FTB 3538 if I owe nothing?
No. A zero-balance voucher should be retained for records but never mailed. Mailing it creates noise in the FTB’s posting system.
Is the $800 annual tax due even on extension?
Yes. The automatic extension covers filing the return, not paying the tax. The $800 is due March 15 for calendar-year filers.
Can a single-member LLC use FTB 3538?
No. A disregarded single-member LLC files Form 568 and uses FTB 3538 only if it owes a balance after Form 3522 has been paid.
Do I write the FEIN or the SOS number in Field 2?
Yes to the SOS file number — Field 2 is for the California Secretary of State number only. The FEIN goes in Field 3, never Field 2.
Does the LP or LLP suffix matter in the entity-name box?
Yes. The FTB’s match algorithm checks the suffix. Dropping LP causes a name-control mismatch and routes the payment to the suspense file.
Can I pay by credit card?
Yes. ACI Payments accepts Visa, MasterCard, Discover, and American Express, with a 2.3% convenience fee.
What if my fiscal year ends mid-year?
Yes, fiscal-year filers use FTB 3538. Enter the actual short-period dates in Field 1 and use the voucher for the year the period began.
Does the extension payment go on Line 1 or Line 2?
Yes, Line 1 is the tentative total tax, and Line 2 is the amount you are sending today. Subtract prior payments from Line 1 to get Line 2.
Can I staple my check to the voucher?
No. Stapling triggers manual processing and adds up to 30 days to posting. Use a paper clip in a separate envelope flap if needed.
Does Web Pay replace the paper voucher?
Yes. When you pay through Web Pay, the FTB has all the data it needs and the paper voucher should not be mailed.
What is the deadline for the 2025 voucher?
Yes, the deadline matters — March 15, 2026 for 2025 calendar-year LPs, LLPs, and REMICs filing Form 565 or 568, per R&TC §18633.
Can an out-of-state LP use FTB 3538?
Yes. Any LP registered to do business in California owes the $800 under R&TC §17935 and uses FTB 3538 for any extension payment.
Do REMICs need an SOS number?
No. REMICs that are federal trusts and not registered with the California SOS leave Field 2 blank and rely on the FEIN.
Can I get a penalty waived if I file late?
Yes, first-time filers may qualify for one-time abatement under R&TC §19132.5 by submitting Form FTB 2917.
Related reading
- How to Fill Out FTB Form 3522 (w/Examples) + FAQs
- How to Fill Out California Form 565 (w/Examples) + FAQs
- How to Fill Out California Form FTB 3539 (w/Examples) + FAQs
- How to Fill Out California Form FTB 3567 (w/Examples) + FAQs
- How to Fill Out California Form FTB 3582 (w/Examples) + FAQs
- How to Fill Out California Form FTB 3805V (w/Examples) + FAQs
- How to Fill Out California Form 100 (w/Examples) + FAQs