Key 2026 Tax Deadlines Every Small Business Owner Must Know
Stay ahead of the IRS with this comprehensive guide to 2026 federal tax deadlines for small businesses, including quarterly estimated taxes, payroll filings, and annual returns.
By Moore CPA Team
Missing a tax deadline can result in costly penalties and unnecessary stress. Here's your complete guide to the tax dates that matter most for small business owners in 2026.
Quarterly Estimated Tax Payments
If your business expects to owe $1,000 or more in taxes, you're required to make quarterly estimated payments:
- Q1: April 15, 2026
- Q2: June 15, 2026
- Q3: September 15, 2026
- Q4: January 15, 2027
Missing these dates results in an underpayment penalty, even if you pay everything by April 15 the following year.
Payroll Tax Deadlines
Employers must deposit federal payroll taxes (Social Security, Medicare, and income tax withholding) either semi-weekly or monthly, depending on your deposit schedule. Form 941 quarterly reports are due by the last day of the month following the quarter end.
Annual Return Deadlines
- S-Corps and Partnerships (Form 1065/1120-S): March 15, 2026
- C-Corps (Form 1120): April 15, 2026
- Individual Returns (Form 1040): April 15, 2026
- Nonprofit Returns (Form 990): May 15, 2026
Extensions
Filing an extension gives you more time to file, but NOT more time to pay. Any tax owed is still due by the original deadline. Extensions push the filing deadline by 6 months.
What Happens If You Miss a Deadline?
The failure-to-file penalty is 5% per month on unpaid taxes, up to 25%. The failure-to-pay penalty is 0.5% per month, also up to 25%. These penalties stack with interest.
Bottom line: Mark these dates on your calendar, set reminders, and if you're unsure about your obligations, contact us. A quick consultation now can prevent expensive mistakes later.