Strategy Snapshot
This page covers tax year 2025 filings that mostly come due during calendar year 2026. In practice, March, April, September, and October are the four dates that control most individual and business compliance.
Calendar-year partnerships and S-Corps, which are due on March 16, 2026 because March 15 falls on a Sunday.
Individuals, C-Corps, first-quarter estimates, FBAR season, and foreign-owned single-member LLC filings.
Confusing an extension to file with an extension to pay; tax is still generally due by the original deadline.
Individual Tax Returns
April 15, 2026: Form 1040 due for calendar-year individual filers. Also the deadline for:
- IRA contributions for the 2025 tax year
- First quarter 2026 estimated tax payment (Form 1040-ES)
- FinCEN 114 (FBAR), due April 15 with automatic extension to October 15
October 15, 2026: Extended deadline for individual returns (Form 1040) if Form 4868 was filed by April 15.
Business Returns
March 16, 2026: Returns due for:
- S-Corporations (Form 1120-S), calendar year
- Partnerships (Form 1065), calendar year
April 15, 2026: Returns due for:
- C-Corporations (Form 1120), calendar year
- Foreign-owned single-member LLCs (pro forma 1120 + Form 5472), calendar year
September 15, 2026: Extended deadline for S-Corp and Partnership returns
October 15, 2026: Extended deadline for C-Corp returns
Estimated Tax Payments (2025)
| Payment | Period Covered | Due Date |
|---|---|---|
| Q1 2025 | Jan 1 – Mar 31 | April 15, 2025 |
| Q2 2025 | Apr 1 – May 31 | June 16, 2025 |
| Q3 2025 | Jun 1 – Aug 31 | September 15, 2025 |
| Q4 2025 | Sep 1 – Dec 31 | January 15, 2026 |
Underpayment penalties apply if you owe more than $1,000 at filing and haven’t paid at least 90% of the current year tax or 100% of prior year tax (110% if prior year AGI exceeded $150,000).
Payroll Tax Deposits
Payroll deposit deadlines depend on your deposit schedule (monthly or semi-weekly) determined by your lookback period. Semi-weekly depositors must deposit:
- Payroll paid Wednesday–Friday → deposit by following Wednesday
- Payroll paid Saturday–Tuesday → deposit by following Friday
January 31, 2026: W-2s and 1099-NECs due to recipients and IRS/SSA
February 28, 2026: Paper 1099s due to IRS (electronic filers: March 31)
International Filing Deadlines
April 15, 2026: Form 5472 (with pro forma 1120) for foreign-owned U.S. LLCs
April 15, 2026 (automatic extension to October 15): FinCEN 114 (FBAR) for foreign financial accounts exceeding $10,000 in aggregate
June 15, 2026: Form 1040 for U.S. citizens and residents living abroad (automatic 2-month extension; no Form 4868 required)
Missing a Deadline
The failure-to-file penalty is generally 5% of unpaid tax per month, up to 25%. The failure-to-pay penalty is 0.5% per month. Interest accrues on unpaid balances at the federal short-term rate plus 3 percentage points.
An extension buys time to finish the paperwork. It does not buy time to pay the tax.Extension misconception
If you cannot file on time, always file an extension and pay as much as possible by the original deadline. Extensions extend the filing date, not the payment deadline.
Last updated: 2026