Important Tax Filing Deadlines Every Business Owner Should Know

Feb 28
1 min read

Missing a tax deadline can result in penalties and interest charges, so staying on top of due dates is crucial. Here’s a guide to key tax filing deadlines for business owners.

1. Quarterly Estimated Tax Payments

Self-employed individuals and businesses that don’t have taxes withheld must make estimated payments on these dates:

📅 Q1: April 15

📅 Q2: June 15

📅 Q3: September 15

📅 Q4: January 15 (of the following year)

2. Business Tax Return Deadlines

Different business structures have different filing deadlines:

📅 March 15 – S-Corporations (Form 1120S) & Partnerships (Form 1065)

📅 April 15 – Sole Proprietors (Schedule C) & C-Corporations (Form 1120)

📅 May 15 – Non-Profit Organizations (Form 990)

3. Payroll Tax Deadlines

Businesses with employees must file payroll taxes regularly:

📅 Monthly/Quarterly Filings – Depending on IRS schedule (Form 941)

📅 Annual Filings – W-2s & 1099s must be sent to employees/contractors by January 31

4. State Tax Deadlines

Many states have additional filing deadlines for income, sales, and payroll taxes. Be sure to check with your state’s tax authority.

5. Filing Extensions

If you need more time:

✅ March 15 Extension: Extends S-Corp & Partnership filings to September 15

✅ April 15 Extension: Extends Sole Proprietor & C-Corp filings to October 15

Final Thoughts

Missing tax deadlines can be costly. Mark these dates on your calendar and work with a tax professional to ensure compliance. Need help staying on track? KB2 Bookkeeping & Tax has you covered! Contact us today for expert tax planning.