California has more tax deadlines than any other state we practice in. Between the IRS, the Franchise Tax Board (FTB), the California Department of Tax and Fee Administration (CDTFA), the Employment Development Department (EDD), and city business-license offices in Downey, Long Beach, and neighboring cities, a growing business easily has 20+ filing dates a year.
This is the 2026 master calendar we give every S&S CPA INC client, organized by quarter. Bookmark it, and if a date is missing from your accounting system today, add it now.
First quarter (January – March 2026)
January 15: Fourth-quarter 2025 federal and California estimated tax payment due for individuals and pass-through entities.
January 31: W-2s and 1099-NEC forms due to recipients and to the IRS/SSA. California DE 9 and DE 9C payroll returns for Q4 2025 due to EDD.
March 16, 2026 (March 15 falls on a Sunday): S-Corporation (Form 1120-S) and Partnership (Form 1065) federal returns due, along with California Form 100S / 565 / 568 and all K-1s to owners. If you need more time, file Form 7004 to extend to September 15.
Second quarter (April – June 2026)
April 15: Individual (1040), C-Corp (1120), and single-member LLC returns due. First-quarter 2026 estimated tax payment due. This is also the deadline for California LLCs to pay the estimated LLC fee (Form 3536) if 2026 gross receipts are projected above $250,000.
April 15: California $800 minimum franchise tax due for LLCs, S-Corps, and corporations (paid via Form 3522 for LLCs).
April 30: Q1 2026 payroll returns (Form 941 federal, DE 9/DE 9C California) due.
June 15: Second-quarter 2026 estimated tax payment due. Deadline to make the annual California Pass-Through Entity (PTE) tax election and payment.
Third quarter (July – September 2026)
July 31: Q2 2026 payroll returns due.
September 15: Third-quarter 2026 estimated tax payment due. Extended S-Corp (1120-S) and Partnership (1065) returns due — this is a firm deadline with no further extension.
Fourth quarter (October – December 2026)
October 15: Extended individual (1040) and C-Corp (1120) returns due. Extended California returns also due.
October 31: Q3 2026 payroll returns due.
December 15: Fourth-quarter estimated payment for C-Corporations.
December 31: Deadline to establish most retirement plans (except SEP-IRAs, which can be set up through the return due date) and to complete year-end tax planning moves.
Sales tax and local filings
CDTFA sales tax returns are due monthly, quarterly, or annually depending on your assigned filing frequency. Most Downey and Los Angeles County retailers we work with file quarterly, with returns due the last day of the month following quarter end (April 30, July 31, October 31, January 31).
City business tax returns vary. Downey renews annually in early spring; Long Beach, Norwalk, Bellflower, and Pico Rivera each have their own schedules. Ask your CPA to confirm your city's cycle in writing so it is not missed.
Frequently asked questions
What happens if I miss the March 15 S-Corp deadline?
The penalty is roughly $220 per shareholder per month (up to 12 months). A two-shareholder S-Corp that files three months late owes over $1,300 in federal late-filing penalties alone. File Form 7004 by March 15 if the return is not ready.
Do I owe California's $800 fee in my first year?
For LLCs formed in California, the first-year exemption that applied to some entities in 2021–2023 has expired. Assume $800 is due in the first year unless your CPA confirms an exemption applies to your specific entity type.
Conclusion
Deadlines are the cheapest part of tax compliance to get right — they cost nothing but a calendar entry, and missing one costs hundreds to thousands of dollars per filing. If you would like our calendar synced to yours, contact S&S CPA INC and we will send the .ics file.
Need Professional Tax or Accounting Advice?
Schedule a complimentary consultation with Selim Hanna, CPA, Managing Partner & Lead CPA, to discuss tax preparation, tax planning, bookkeeping, CFO advisory, IRS representation, or business consulting services.
Selim Hanna is a licensed Certified Public Accountant with prior Big 4 accounting experience, licensed to practice in California, Colorado, and Tennessee. He leads S&S CPA INC's Tax Planning, Accounting, Bookkeeping, CFO Advisory, IRS Representation, and Attestation Services practices for closely held businesses and high-earning professionals.
The information provided in this article is for educational purposes only and should not be considered tax, accounting, or legal advice. Every situation is unique. Contact S&S CPA INC for advice tailored to your specific circumstances.