Federal business tax payment due dates by entity type follow two calendar-year anchors: March 15 for S corporations and partnerships, and April 15 for C corporations and sole proprietors. Quarterly estimated payments sit on top of those annual deadlines, and payroll taxes run on their own schedule. Miss any of them and penalties plus daily interest start immediately.
When the Deadline Falls on a Weekend or Holiday
One rule cuts across every entity type. If a federal tax deadline lands on a Saturday, Sunday, or legal holiday, it shifts to the next business day. In 2026, March 15 is a Sunday, so S corporations and partnerships have until Monday, March 16. April 15, 2026 is a Wednesday, so the C corp and sole proprietor deadline holds. “Legal holiday” includes any holiday recognized in the District of Columbia, plus statewide holidays where an IRS office is located.1Office of the Law Revision Counsel. 26 USC 7503 – Time for Performance of Acts Where Last Day Falls on Saturday, Sunday, or Legal Holiday
C Corporation Deadlines
A C corporation owes its federal income tax by the 15th day of the fourth month after the close of its tax year. For calendar-year filers, that’s April 15.2Office of the Law Revision Counsel. 26 USC 6072 – Time for Filing Income Tax Returns Form 1120 and the payment share the same date, so the full balance is due even if you request more time to file the return itself.
There’s one fiscal-year exception worth flagging. C corporations with a tax year ending June 30 must file and pay by the 15th day of the third month after year-end, not the fourth.3Internal Revenue Service. Starting or Ending a Business 3 That’s one fewer month than every other C corp gets. Any other fiscal year end uses the standard fourth-month rule.
S Corporation and Partnership Deadlines
S corporations and partnerships file a month earlier. Their returns and any entity-level taxes are due by the 15th day of the third month after the tax year ends, which is March 15 for calendar-year entities.2Office of the Law Revision Counsel. 26 USC 6072 – Time for Filing Income Tax Returns
These entities usually pass income through to owners, who then pay tax on their personal returns. The entity itself can still owe tax in some situations. An S corporation with built-in gains from a prior C corporation conversion, or one with excess passive investment income, will owe entity-level tax by the same March deadline. Missing it triggers penalties against the entity, no matter what each owner does on a personal return.
Multi-member LLCs that haven’t elected corporate treatment are taxed as partnerships by default, so they follow the same March 15 timeline.
Sole Proprietors and Single-Member LLCs
Sole proprietors report business income on Schedule C, filed with Form 1040. The payment deadline is April 15 for calendar-year filers, the same as personal income tax.3Internal Revenue Service. Starting or Ending a Business 3 Single-member LLCs that haven’t elected corporate tax treatment work the same way, because the IRS treats them as disregarded entities.
If your LLC has elected S corporation or C corporation treatment, use that entity’s deadlines instead.
Quarterly Estimated Payments for Corporations
The federal system is pay-as-you-go. A corporation that expects to owe $500 or more when it files must send quarterly estimated payments during the year.4Internal Revenue Service. Underpayment of Estimated Tax by Corporations Penalty For calendar-year corporations, the four installment dates are:
- 1st installment: April 15
- 2nd installment: June 15
- 3rd installment: September 15
- 4th installment: December 15
Those dates come straight from the statute and apply to C corporations.5Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax The fourth installment falls in December, not January, which trips people up because individuals have until January 15 for their final quarterly payment. Fiscal-year corporations use the 4th, 6th, 9th, and 12th months of their tax year.4Internal Revenue Service. Underpayment of Estimated Tax by Corporations Penalty
Each installment is 25% of the required annual payment, which is the lesser of 100% of the current year’s tax or 100% of the prior year’s tax.5Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
Large Corporation Rules
If your corporation had taxable income of $1 million or more in any of the three preceding tax years, the IRS treats it as a “large corporation” for estimated tax purposes.6eCFR. 26 CFR 1.6655-4 – Large Corporations Large corporations can’t base payments on last year’s tax. They have to use 100% of the current year’s liability. The first installment can still use the prior year’s figure, but any shortfall has to be added to the second installment.5Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax Mid-size companies coming off a strong year often get caught here.
S corporations and partnerships don’t make corporate estimated payments in the same way, because their income flows through to owners who handle estimates on their personal returns.
Payroll Tax Deadlines
Income tax isn’t the only payment the IRS expects. Any business with employees deposits withheld income tax, Social Security, and Medicare on a monthly or semi-weekly schedule depending on payroll size, then reports on Form 941 each quarter:7Internal Revenue Service. Instructions for Form 941 (03/2026)
- Q1 (January–March): April 30
- Q2 (April–June): July 31
- Q3 (July–September): October 31
- Q4 (October–December): January 31
Form 941 reconciles the quarter’s deposits. If every deposit was on time and in full, you get an extra 10 days to file the form.7Internal Revenue Service. Instructions for Form 941 (03/2026)
An Extension to File Is Not an Extension to Pay
This is the single most expensive misunderstanding in business tax compliance. Filing Form 7004 gives your company an automatic six-month extension to submit the return.8Internal Revenue Service. About Form 7004, Application for Automatic Extension of Time to File Certain Business Income Tax, Information, and Other Returns It does not extend the payment deadline. The full estimated balance has to reach the IRS by the original due date.9Internal Revenue Service. Instructions for Form 7004
File an extension without paying, and interest starts accruing the day after the original deadline, on top of the failure-to-pay penalty. The extension buys time for paperwork only.
What Late Payment Costs
The IRS applies two separate penalties, and they can stack.
The failure-to-pay penalty is 0.5% of the unpaid tax for each month or partial month the balance is outstanding, capped at 25%.10Internal Revenue Service. Failure to Pay Penalty Even one day into a new month counts as a full month.
The failure-to-file penalty is heavier: 5% of unpaid tax per month, up to the same 25% cap. When both apply in the same month, the filing penalty is reduced by the payment penalty amount, so the combined charge runs at 5% per month rather than 5.5%. The filing penalty maxes out after five months; the payment penalty keeps running until you pay.11Internal Revenue Service. Failure to File Penalty If you can only do one, file on time.
Interest runs on top of the penalties. The rate adjusts quarterly at the federal short-term rate plus three percentage points. The corporate underpayment rate is 7% for the first quarter of 2026 and 6% for the second quarter.12Internal Revenue Service. Quarterly Interest Rates Large corporate underpayments above $100,000 carry an extra two percentage points.13Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 Interest compounds daily.
How to Pay
The IRS offers several channels for business payments:14Internal Revenue Service. Payments
- EFTPS (Electronic Federal Tax Payment System) is the primary method for business deposits. It’s free, but enrollment takes time, so sign up before you need it. Payments scheduled through EFTPS must be submitted by 8 p.m. ET the day before the due date to count as timely.
- The IRS Business Tax Account is a newer online portal for deposits and balance-due payments.
- Same-day wire through your bank works for last-minute payments, usually with a bank fee.
- Check or money order can be mailed with a payment voucher.
- Electronic funds withdrawal is available when e-filing a return.
Businesses required to make federal tax deposits, which includes payroll taxes, corporate estimated payments, and excise taxes, generally have to deposit electronically. EFTPS is the most common route, and same-day wires or ACH credit through a financial institution also satisfy the requirement.
If You Miss a Deadline
The IRS may waive penalties under its reasonable-cause standard if you can show you exercised ordinary business care and prudence but still couldn’t comply.15Internal Revenue Service. Penalty Relief for Reasonable Cause Circumstances that typically qualify include natural disasters or fires that destroyed records, serious illness or death of a key person responsible for tax compliance, inability to obtain necessary records despite reasonable efforts, and system failures that blocked timely electronic filing or payment.
A cash shortage on its own doesn’t qualify. The underlying cause of the shortage sometimes does, such as a major client’s bankruptcy that made it impossible to meet payroll and tax obligations at the same time. Send documentation with your request: hospital records, insurance claims, correspondence showing the disruption.15Internal Revenue Service. Penalty Relief for Reasonable Cause Relief waives the penalty only. Interest on the unpaid balance keeps accruing.