Colorado Small Business Tax & Filing Calendar
This comprehensive filing calendar outlines the essential deadlines for small businesses operating in Colorado. It covers various entity types, including S Corporations, Partnerships, C Corporations, and Sole Proprietorships/Single-Member LLCs.
1. Federal Income Tax Deadlines
S Corporations (Form 1120-S) & Partnerships (Form 1065)
- Annual Return: Due the 15th day of the 3rd month after the end of the tax year. For calendar year entities, this is March 15.
- Extension Deadline: September 15.
C Corporations (Form 1120)
- Annual Return: Due the 15th day of the 4th month after the end of the tax year. For calendar year entities, this is April 15.
- Extension Deadline: October 15.
Sole Proprietorships & Single-Member LLCs (Schedule C)
- Annual Return: Due with personal 1040 returns on April 15.
- Extension Deadline: October 15.
2. Colorado State Income Tax Deadlines
Colorado generally follows federal deadlines for income tax filing.
| Entity Type | Colorado Form | Deadline (Calendar Year) |
|---|---|---|
| S Corp | Form 106 | April 15 |
| Partnership | Form 106 | April 15 |
| C Corp | Form 112 | April 15 |
| Individual/Sole Prop | Form 104 | April 15 |
Note: While federal partnership/S Corp returns are due March 15, Colorado Form 106 is generally due April 15.
3. Federal & State Estimated Tax Payments
Estimated taxes are required if you expect to owe $1,000 or more (Federal) or $1,000 or more (Colorado) when you file.
- Q1: April 15
- Q2: June 15
- Q3: September 15
- Q4: January 15 (following year)
4. Payroll Tax Deadlines (Federal & State)
If your business has employees, you must adhere to strict payroll cycles.
Federal (IRS)
- Form 941 (Employer’s Quarterly Federal Tax Return): Due April 30, July 31, Oct 31, Jan 31.
- Form 940 (FUTA): Annual filing due Jan 31.
- W-2/W-3 Filing: Due to employees and Social Security Administration by January 31.
Colorado (CDLE & DOR)
- Unemployment Insurance (Form UITR): Quarterly reports and payments due the last day of the month following the quarter-end (April 30, July 31, Oct 31, Jan 31).
- Wage Withholding: Frequency (Weekly, Monthly, or Quarterly) depends on the amount withheld. Quarterly filers follow the standard end-of-month deadlines.
5. Sales & Use Tax (Colorado)
Sales tax filing frequency is determined by the Colorado Department of Revenue based on your sales volume.
- Monthly: Due the 20th of the following month.
- Quarterly: Due the 20th of the month following the quarter-end (April 20, July 20, Oct 20, Jan 20).
- Annual: Due January 20.
6. Personal Property Tax (Colorado)
In Colorado, businesses must pay tax on personal property (equipment, furniture, etc.) used to produce income.
- Declaration Schedule: Must be filed with the County Assessor by April 15 each year.
- Payment: Tax bills are typically sent in January; first half is due February 28, second half due June 15 (or full payment by April 30).
7. Colorado Periodic Report (Annual Report)
All registered entities (LLCs, Corporations) must file a Periodic Report with the Colorado Secretary of State to remain in “Good Standing.”
- Deadline: Every year during a three-month window that opens on the first day of the anniversary month of the business formation.
- Example: If you formed your LLC in May, your window is May 1 through July 31.
Summary Checklist for Calendar Year 2025/2026
| Date | Obligation |
|---|---|
| Jan 15 | Q4 Estimated Tax Payment |
| Jan 20 | Sales Tax (Monthly/Quarterly/Annual) |
| Jan 31 | W-2s to Employees; Forms 941, 940, and UITR |
| Feb 28 | 1st Half Personal Property Tax Payment |
| Mar 15 | Federal S Corp & Partnership Returns |
| Apr 15 | Federal & State Individual/C-Corp Returns; Q1 Estimated Tax; Property Tax Declaration |
| Apr 20 | Q1 Sales Tax |
| Apr 30 | Q1 Payroll Taxes (941/UITR); Full Property Tax Payment |
| Jun 15 | Q2 Estimated Tax; 2nd Half Personal Property Tax |
| Jul 20 | Q2 Sales Tax |
| Jul 31 | Q2 Payroll Taxes (941/UITR) |
| Sep 15 | Q3 Estimated Tax; Extended S Corp/Partnership Deadline |
| Oct 15 | Extended Individual/C-Corp Deadline |
| Oct 20 | Q3 Sales Tax |
| Oct 31 | Q3 Payroll Taxes (941/UITR) |
Disclaimer: This calendar is for informational purposes only. Tax laws vary by specific business circumstances and change frequently. Consult with a qualified Colorado CPA or tax professional to ensure compliance with all local, state, and federal requirements for Colorado small business tax.