Tax deadlines creep up fast for growing startups, especially once you’re operating in multiple states and cities. This 2026 calendar brings together key federal, state, and local dates that most venture-backed startups encounter, including income tax, payroll, sales and use tax, R&D credits, and city-level filings.
Use this as a planning tool to sync with your finance, payroll, and people teams, build reminders into your systems, and avoid last-minute scrambles that can derail a fundraise or audit. This calendar is for general informational purposes only and should not be relied on as tax, legal, or accounting advice. Always consult your tax advisor about your specific situation.
2026 U.S. Tax Deadlines for Startups
The table below summarizes many of the key 2026 federal and multi-state deadlines that affect startups, including income tax filings, estimated payments, R&D credits, and recurring sales and use tax filings.
| Date |
Deadline / Description |
| JAN 15–31 |
- Monthly, Quarterly, Semi-annual, and Annual Sales/Use Tax Returns
|
JAN 31
(Saturday → Due Monday, February 2, 2026) |
|
| FEB 15–28 |
- Monthly Sales/Use Tax Returns
|
FEB 28
(Saturday → Due Monday, March 2, 2026) |
- 1099-MISC – if paper-filing (due March 31 if e-filing). Additional 30 days extension – File Form 8809
- Form 3921 – if paper-filing (due March 31 if e-filing)
- IRS ACA Compliance Forms 1094-B, 1095-B, 1094-C, and 1095-C – if paper-filing (due March 31 if e-filing). Additional 30 days extension – File Form 8809
|
| MAR 1 |
|
| MAR 15–31 |
- Monthly Sales/Use Tax Returns
|
| MAR 16 |
- Federal and State income tax return for S-Corp and Partnership; or Federal and State income tax extension filing for S-Corp and Partnership
- Forms 1042, 1042-S, or Extension to file can be requested by this date (filing and furnishing copies to the recipient)
- Deadline to elect S corporation status for 2026 (Form 2553)
|
| MAR 31 |
- Last day to file Federal income tax return with R&D Credit in order to utilize the credit towards payroll tax in Q2
|
| APR 15 |
- Federal and State income tax return of Individuals and Corporations; or Federal and State income tax extension filing for Individuals and Corporations
- Federal Quarterly Estimated Taxes (Q1)
- FinCEN 114 – FBAR (will be allowed to extend)
- California Corporate estimated tax (Form 100-ES) 1st installment due
|
| APR 15–30 |
- Monthly Sales/Use Tax Returns
|
| APR 30 |
- R&D Tax Credit Form 941 to claim R&D credit against payroll taxes
|
| MAY 15 |
- Form 990 Series – Tax-Exempt Organizations
- Form 8868 – Application for Extension of Time to File an Exempt Organization Return
|
| MAY 15–31 |
- Monthly Sales/Use Tax Returns
|
| JUN 1 |
|
| JUN 15 |
- Federal Quarterly Estimated Taxes (Q2)
|
| JUN 15–30 |
- Monthly Sales/Use Tax Returns
|
| JUN 30 |
- Last day to file Federal income tax return with R&D Credit in order to utilize the credit towards payroll tax in Q3
|
| JUL 15–31 |
- Monthly, Quarterly, Semi-annual, and Annual Sales/Use Tax Returns
|
| JUL 31 |
- Annual Return/Report of Employee Benefit Plan
- R&D Tax Credit Form 941 to claim R&D credit against payroll taxes
|
| AUG 15–31 |
- Monthly Sales/Use Tax Returns
|
| SEP 1 |
|
| SEP 15 |
- Federal Quarterly Estimated Taxes (Q3)
- Federal and State income tax return for S-Corp and Partnership with filed extension
- Form 1042 extended filing deadline
|
| SEP 15–30 |
- Monthly Sales/Use Tax Returns
|
| SEP 30 |
- Form 1041 Extended Return
- Last day to file Federal income tax return with R&D Credit in order to utilize the credit towards payroll tax in Q4
|
| OCT 15 |
- Federal and State income tax return for Individuals and Corporations with filed extension
- FinCEN 114 (Extended return)
- Form 5500 Series Extended Return
|
| OCT 15–31 |
- Monthly, Quarterly, and Annual Sales/Use Tax Returns
|
OCT 31
(Saturday → Due Monday, November 2, 2026) |
- R&D Tax Credit Form 941 to claim R&D credit against payroll taxes
|
| NOV 15–30 |
- Monthly Sales/Use Tax Returns
|
| NOV 16 |
- Federal and State income tax return for Exempt Organizations with filed extension
|
| DEC 1 |
|
| DEC 15 |
- Federal Quarterly Estimated Taxes (Q4)
|
| DEC 15–31 |
- Monthly Sales/Use Tax Returns
|
| VARIABLE |
- Secretary of State / Annual Reports
|
San Francisco Additional 2026 Tax Deadlines for Startups
San Francisco startups face their own layer of business registration, gross receipts, payroll, rent, and property tax filings. Use this list alongside the federal calendar when planning cash flow and compliance.
| Date |
Deadline / Description |
FEB 28
(Saturday → Due Monday, March 2, 2026) |
- San Francisco Annual Gross Receipts, Payroll, and Rent Tax Returns (60-day extension is available for filing the tax return, but not for paying any tax due)
- San Francisco Quarterly (Q4-2025) Estimated Gross Receipts Tax Payment
|
| APR 1 |
- SF 571-L California Business Personal Property Tax Filing Due – Initial deadline
|
| APR 10 |
- Second installment deadline to pay the property tax bill to San Francisco County
|
| APR 30 |
- San Francisco Quarterly (Q1) Estimated Tax Payment
|
| MAY 7 |
- SF 571-L California Business Personal Property Tax Filing – Final date to avoid a 10% penalty
|
| MAY 31 |
|
| JUL 31 |
- San Francisco Quarterly (Q2) Estimated Tax Payments
|
| AUG 31 |
- SF 571-L Business Personal Property Tax Payment Due
|
| OCT 31 |
- San Francisco Quarterly (Q3) Estimated Tax Payments
|
| DEC 10 |
- San Francisco County Property Tax Bill – First installment
|
| VARIABLE |
|
New York Additional 2026 Tax Deadlines for Startups
New York startups need to track NYS, NYC, and local sales and use tax filings, as well as estimated tax payments and extensions. The dates below supplement the federal calendar above.
| Date |
Deadline / Description |
| JAN 15 |
- NY Estimated Tax Payment Q4 of 2024 – Individual, Partnership, and S-Corp
|
| JAN 20 |
- NY Sales/Use Tax Return Due for Monthly Filers
|
| FEB 20 |
- NY Sales/Use Tax Return Due for Monthly Filers
|
| MAR 16 |
- Federal and NY State and NYC income tax return for S-Corp and Partnership; or
- NYS and NYC mandatory first installment of estimated tax
- Federal and NY State and NYC income tax extension filing for S-Corp and Partnership
|
| MAR 20 |
- NY Sales/Use Tax Return Due for Monthly, Quarterly, and Annual Filers
|
| APR 21 |
- NY Sales/Use Tax Return Due for Monthly Filers
|
| MAY 20 |
- NY Sales/Use Tax Return Due for Monthly Filers
|
| JUN 15 |
- NY Estimated Tax Payments
|
| JUN 20 |
- NY Sales/Use Tax Return Due for Monthly & Quarterly Filers
|
| JUL 20 |
- NY Sales/Use Tax Return Due for Monthly Filers
|
| AUG 20 |
- NY Sales/Use Tax Return Due for Monthly Filers
|
| SEP 15 |
- NY Estimated Tax Payments
- Federal and NY State income tax return for S-Corp and Partnership with filed extension
|
| SEP 20 |
- NY Sales/Use Tax Return Due for Monthly & Quarterly Filers
|
| OCT 20 |
- NY Sales/Use Tax Return Due for Monthly Filers
|
| NOV 20 |
- NY Sales/Use Tax Return Due for Monthly Filers
|
| DEC 15 |
- NY Corporation Estimated Tax Payments
|
| DEC 2 |
- NY Sales/Use Tax Return Due for Monthly & Quarterly Filers
|
| VARIABLE |
- Annual renewal of your business license
|
Seattle Additional 2026 Tax Deadlines for Startups
Seattle and Washington State add another layer of business license and excise tax deadlines. The dates below highlight key 2026 obligations for startups operating in Seattle.
| Date |
Deadline / Description |
| JAN 31 |
- Prior year Q4 Seattle Business License Tax for Quarterly Filers
|
| APR 15 |
- Washington Annual Excise Tax Return (Business & Occupation Tax)
|
| APR 30 |
- Washington Q1 Excise Tax Return (Business & Occupation Tax)
- Washington Personal Property Tax Listing Form and 50% of property taxes
- Seattle Business License Tax Deadline for Annual Filers
|
| JUL 31 |
- Washington Q2 Excise Tax Return (Business & Occupation Tax)
- Seattle Q2 Business License Tax for Quarterly Filers
|
| OCT 31 |
- Washington Personal Property Tax due (remaining 50%)
- Washington Q3 Excise Tax Return (Business & Occupation Tax)
- Seattle Q3 Business License Tax for Quarterly Filers
|
| VARIABLE |
- Annual renewal of your business license
|
Need Help Navigating 2026 Tax Deadlines?
Coordinating federal, state, and city tax deadlines across multiple entities and jurisdictions can be a heavy lift for a lean startup finance team. Missed dates create penalties, interest, and avoidable friction in future fundraising and due diligence.
Burkland’s tax professionals help startups stay compliant, optimize R&D credits, and plan cash flow around key filing and payment dates. Reach out to Burkland’s tax team for support.
