As the year winds down, small business owners across Colorado face one of the most important administrative windows of the year: the final chance to get their books in order, secure every legal deduction, and prepare for upcoming state and federal tax obligations. December is more than a time to reflect — it’s the last opportunity to reduce your tax burden before December 31 and avoid surprises when filing in early 2026. This guide walks through the essential tasks Colorado business owners should complete during the last month of the year, why they matter, and the specific deadlines you do not want to miss.
Review Your Profit & Loss Statement With a Critical Eye
Your year-end P&L isn’t just another report. It’s the clearest snapshot of how your business performed in 2025. Set aside time to compare month-to-month revenue trends, identify unexpected expense spikes, and verify that all income has been accurately recorded. For Colorado service businesses — contractors, agencies, trades, professional services — ensure deposits match invoices and payments recorded in your accounting platform.
One overlooked area is reimbursements. If owners or employees used personal cards for business expenses but never submitted them, you may be missing deductible items. Cleaning this up before December 31 reduces taxable profit and prevents messy corrections during tax season.
Maximize Deductions Before December 31
Many deductions only count if the purchase or payment is made on or before December 31, 2025. That means you still have time in December to make strategic financial moves.
Common Year-End Deduction Opportunities
- Equipment purchases: Section 179 and bonus depreciation may still apply for qualifying assets placed into service by year-end.
- Software & subscriptions: Annual renewals paid in December can count for 2025.
- Mileage logs: Colorado small business owners using the standard mileage deduction must have updated logs for the year.
- Home office expenses: Ensure square footage, utilities, and internet allocations are accurate.
- Retirement contributions: SEP IRA and solo 401(k) deadlines vary, but employer contributions often can be made by your tax filing date. Employee deferrals, however, must be elected by December 31.
A surprising number of business owners lose money simply because they fail to document deductions properly. Taking these steps now ensures you’re not guessing when filing your return.
Organize Receipts & Reconcile Accounts
Some businesses are disciplined all year. Others spend December digging through glove compartments, email inboxes, and credit card statements. Wherever you fall on the spectrum, completing these tasks before year-end is vital:
- Match receipts to every expense over $75.
- Reconcile bank and credit card accounts through November (and December if possible).
- Digitize physical receipts to avoid loss.
- Mark any personal expenses on business cards to prevent IRS issues.
- Check vendor 1099-NEC requirements — especially for contractors paid more than $600.
Colorado business owners often forget that vendor reporting affects your tax season too. Clean records save hours in February.
Prepare for Q4 & Estimated Tax Payments
If your business is profitable, December is your last call to prepare for Q4 estimated tax payments, due:
- Federal: January 15, 2026
- Colorado State: January 15, 2026
Missing or underpaying estimated taxes can lead to penalties from both the IRS and the Colorado Department of Revenue. Review your year-to-date profit and calculate whether your previous estimates were sufficient. If your revenue increased significantly toward the end of 2025, an additional payment in December may prevent a surprise bill.
Key Differences Between Federal and Colorado Year-End Requirements
Not every business owner realizes the deadlines and expectations differ slightly between agencies. This comparison table keeps it simple:
Federal vs. Colorado Year-End Requirements
| Topic | Federal Requirement | Colorado Requirement |
| Estimated Taxes | Q4 payment due Jan 15, 2026, paid via EFTPS or Payment option on IRS.gov | Same deadline, paid through Revenue Online |
| W-2 Distribution | Must provide to employees and file with the Social Security Administration by Jan 31, 2026 | Same deadline; Colorado also requires electronic filing for most employers |
| 1099-NEC Filing Deadline | Feb 1, 2026 | Feb 1, 2026 |
| Sales Tax Filing | No filing requirement | Colorado DR 0100 due Jan 20 for monthly filers |
| Payroll Withholding | Deposit schedules vary | Deposit schedules vary |
Filing deadlines are often adjusted based on liability amount; these changes usually take effect January 1.
Review Payroll, Bonuses, and Contractor Payments
Even if you don’t issue holiday bonuses, you should review payroll thoroughly in December. Confirm:
- Employee addresses are current
- Withholding rates are accurate
- All reimbursable expenses were processed
- All contractor payouts are logged for 1099s
- PTO balances and year-end accruals are recorded
This is especially important for Colorado’s growing compliance environment. With the Healthy Families and Workplaces Act and local minimum wage updates (Denver increases on January 1 each year), accurate payroll records prevent headaches.
Evaluate Your Entity Structure Before Filing Season
Many Colorado businesses discover too late that their tax burden could have been reduced through an S-Corp election or restructuring. December is the ideal time to review:
- Owner salary for S-Corps (“reasonable compensation” requirement)
- Whether your LLC should elect S-Corp status in 2026
- Whether multi-member LLCs need updated operating agreements
- If you plan major changes (buyouts, mergers, adding partners)
A short year-end meeting with your CPA saves thousands long-term.
FAQs: Colorado Small Business Year-End Tax Questions
Do I need to file an annual report with the Colorado Secretary of State?
Yes, but it’s tied to your entity anniversary month — not December. Still, year-end is a good time to check your status.
Do Colorado businesses pay a state franchise tax?
No. Colorado does not have a franchise tax. You still owe income tax (if not an S-Corp), sales tax (if applicable), and payroll taxes.
When should I send 1099s?
Distribute to recipients by January 31, 2026. File with IRS and Colorado by February 1, 2026.
Can equipment purchases in December still count for 2025?
Yes, if placed “in service” before December 31.
Year-end tax preparation isn’t glamorous, but it’s one of the most financially important responsibilities of owning a business. Taking the time in December to organize, verify, and plan sets your business up for a stronger and less stressful year ahead. If you use these steps as your checklist, you’ll enter 2026 confident, compliant, and ready for growth.
Written by Kali TBA Associates
TBA & Associates provides professional accounting and tax services for individuals and businesses throughout Colorado.