When are individual tax returns due in 2026?

Federal individual tax returns (Form 1040) for the 2025 tax year are due April 15, 2026. If you file for an extension, you have until October 15, 2026 to file — but any taxes owed are still due by April 15. California follows the same April 15 deadline for state returns.

When are S-corporation and partnership returns due?

S-corporation returns (Form 1120-S) and partnership returns (Form 1065) are due March 15, 2026 for the 2025 tax year. A 6-month extension can be filed, moving the deadline to September 15, 2026. These deadlines fall before the individual deadline because K-1s from these entities flow to owners' personal returns.

What happens if I miss a tax deadline?

Missing the filing deadline results in a failure-to-file penalty of 5% of unpaid taxes per month, up to 25%. Missing a payment deadline results in a failure-to-pay penalty of 0.5% per month, plus interest. Filing an extension eliminates the failure-to-file penalty but not failure-to-pay. Contact Your Tax Team immediately if you've missed a deadline — we can minimize penalties through penalty abatement requests.

Does a tax extension give me more time to pay?

No. A filing extension only gives you more time to submit your return — it does not extend the time to pay. If you owe taxes, you must pay by the original due date (typically April 15) to avoid the failure-to-pay penalty and interest. You can estimate what you owe and pay that amount with your extension request.

When is the California LLC fee due?

California LLCs pay an $800 annual franchise tax due by the 15th day of the 4th month of the taxable year — for calendar-year LLCs, that is April 15. New LLCs formed in California are exempt from the $800 fee in their first year. The LLC fee (based on gross receipts) is due with the return.

Tax Due Dates 2025–2026 | Federal & California Deadlines

Q: What are the 2026 quarterly estimated tax payment dates?

The four 2026 estimated tax payment due dates are: Q1 — April 15, 2026; Q2 — June 16, 2026; Q3 — September 15, 2026; Q4 — January 15, 2027. If you expect to owe $1,000 or more in federal taxes after withholding, you generally must make estimated payments to avoid an underpayment penalty.

2026 Estimated Tax Payment Dates

If you're self-employed, a business owner, or have income without withholding, you must pay estimated taxes quarterly. Missing these dates triggers an underpayment penalty.

Q1 · Jan–Mar 2026

Apr 15

First quarter payment due

Q2 · Apr–May 2026

Jun 16

Second quarter payment due

Q3 · Jun–Aug 2026

Sep 15

Third quarter payment due

Q4 · Sep–Dec 2026

Jan 15, 2027

Fourth quarter payment due

Safe harbor rule: You avoid the underpayment penalty if you pay at least 100% of last year's tax liability (110% if your AGI exceeded $150,000), or 90% of the current year's tax — whichever is smaller.

2025 Tax Year — Complete Deadline Calendar

All filing and payment deadlines for the 2025 tax year, in chronological order.

Due Date	Who It Applies To	What's Due
Jan 15, 2026	Self-employed, business owners	Q4 2025 estimated tax payment (federal & CA)
Jan 31, 2026	Employers, payers	W-2s and 1099-NECs sent to recipients; filed with SSA/IRS
Feb 18, 2026	Brokers, financial institutions	1099-B, 1099-S, consolidated brokerage statements to recipients
Mar 3, 2026	Farmers & fishermen	File 2025 return and pay all tax (if no estimated payments made)
Mar 15, 2026	S-Corporations, Partnerships, Multi-member LLCs	Form 1120-S (S-Corp) and Form 1065 (Partnership) returns due; or file Form 7004 for 6-month extension to Sep 15
Apr 15, 2026	Individuals, sole proprietors, single-member LLCs	Form 1040 due; or file Form 4868 for extension to Oct 15. All taxes owed must be paid today regardless of extension.
Apr 15, 2026	C-Corporations	Form 1120 due; or file Form 7004 for extension to Oct 15
Apr 15, 2026	Individuals	Q1 2026 estimated tax payment due; IRA & HSA contribution deadline for 2025 tax year
Apr 15, 2026	California LLCs	$800 CA annual franchise tax due for calendar-year LLCs; LLC fee based on gross receipts
Jun 16, 2026	Self-employed, business owners	Q2 2026 estimated tax payment due (federal & CA)
Sep 15, 2026	S-Corporations, Partnerships (extended)	Extended Form 1120-S and Form 1065 returns due
Sep 15, 2026	Self-employed, business owners	Q3 2026 estimated tax payment due (federal & CA)
Oct 15, 2026	Individuals (extended)	Extended Form 1040 due — final deadline, no further extensions
Oct 15, 2026	C-Corporations (extended)	Extended Form 1120 due
Jan 15, 2027	Self-employed, business owners	Q4 2026 estimated tax payment due (federal & CA)

Deadlines by Business Entity Type

Your business structure determines which returns you file and when they're due.

Sole Proprietor / Single-Member LLC

Schedule C (with Form 1040) Apr 15
Extension (Form 4868) Apr 15 → Oct 15
Quarterly estimated payments 4× / year
Self-employment tax (SE tax) With return

S-Corporation (1120-S)

Form 1120-S return due Mar 15
Extension (Form 7004) Mar 15 → Sep 15
K-1s issued to shareholders Mar 15
PTET election & prepayment (CA) Jun 15

Partnership / Multi-Member LLC (1065)

Form 1065 return due Mar 15
Extension (Form 7004) Mar 15 → Sep 15
K-1s issued to partners Mar 15
CA LLC franchise tax ($800) Apr 15

C-Corporation (1120)

Form 1120 return due Apr 15
Extension (Form 7004) Apr 15 → Oct 15
Corporate estimated payments 4× / year
Fiscal year corps: 15th day of 4th month Varies

What Happens If You Miss a Deadline?

Missing deadlines costs real money — and the penalties compound monthly. Here's what you're looking at.

5%

Failure-to-File Penalty

Per month of unpaid taxes, up to a maximum of 25%. The most expensive penalty — avoided entirely by filing on time or filing an extension request.

0.5%

Failure-to-Pay Penalty

Per month on the unpaid balance, up to 25%. Applies even if you filed an extension. Pay as much as you can by the original deadline to minimize this penalty.

+Interest

Interest on Unpaid Tax

The IRS charges interest on unpaid taxes from the due date until paid in full. The rate is the federal short-term rate plus 3% — currently around 7–8% annually.

First-time penalty abatement: If you have a clean compliance history, the IRS may waive the failure-to-file or failure-to-pay penalty for the first offense. Contact Your Tax Team — we handle penalty abatement requests regularly.

Tax Deadline FAQ

Federal individual returns (Form 1040) for the 2025 tax year are due April 15, 2026. File Form 4868 by April 15 to get an automatic extension to October 15. California follows the same April 15 deadline. Remember: an extension only extends the time to file — not the time to pay.

No. A filing extension only gives you more time to submit your paperwork. Any taxes owed must be paid by the original April 15 deadline to avoid the failure-to-pay penalty and interest. Estimate what you owe and pay it with your extension request — you can get a refund later if you overpaid.

S-corp (Form 1120-S) and partnership (Form 1065) returns are due March 15, 2026 for the 2025 tax year — one month before the individual deadline. This is intentional so that K-1s can flow to owners' personal returns. File Form 7004 by March 15 for a 6-month extension to September 15.

The four 2026 estimated tax due dates: Q1 — April 15 | Q2 — June 16 | Q3 — September 15 | Q4 — January 15, 2027. If you expect to owe $1,000 or more in federal taxes after withholding, you generally must make estimated payments to avoid an underpayment penalty.

Missing the filing deadline triggers a failure-to-file penalty of 5% per month (up to 25%). Missing a payment deadline triggers a failure-to-pay penalty of 0.5% per month plus interest. If you've already missed a deadline, file as soon as possible — and contact us. We can often request first-time penalty abatement for clients with a clean history.

For calendar-year California LLCs, the $800 annual franchise tax is due April 15. New LLCs formed in California are exempt from the $800 fee in their first taxable year. The LLC fee (based on gross receipts, ranging from $900 to $11,790) is due with the return by April 15, or by the extended deadline if an extension was filed.

Stay Ahead of Every Deadline — Without the Stress

Your Tax Team proactively tracks deadlines for every client and sends reminders before anything is due. Never worry about penalties again.

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2025–2026 Tax Due Dates: Federal & California