Estimated Tax Payments for Colorado Small Businesses: Schedule and Thresholds

If you own a Colorado small business — whether you operate as a sole proprietor, partnership, LLC, or S-Corp — the IRS and Colorado Department of Revenue expect you to pay income tax as you earn it, not in one lump sum at filing. Missing a quarterly estimated tax deadline costs real money in penalties and interest, and the rules are more nuanced than most Colorado Springs business owners realize. Here's exactly who owes estimated tax, when to pay, how much to send, and the safe harbor thresholds that keep you penalty-free.

Who Needs to Pay Quarterly Estimated Tax?

Federal rules require quarterly estimated tax payments from anyone whose total tax will exceed withholding by $1,000 or more (IRC § 6654(e)(1)). For Colorado small business owners, that typically includes:

• Self-employed individuals (sole proprietors, single-member LLCs) — covers income tax plus the full 15.3% self-employment tax
• Partners and multi-member LLC members receiving Schedule K-1 income
• S-Corporation shareholders on their share of K-1 income (W-2 salary has withholding applied at source; K-1 pass-through income does not)
• C-Corporations expecting to owe $500 or more, paid through EFTPS using the Form 1120-W worksheet

Even a day job with W-2 withholding won't cover you if a side business generates more than a few thousand dollars of untaxed profit — you'll typically need quarterly estimates to stay ahead.

The 2026 Quarterly Schedule

Federal and Colorado individual estimated tax deadlines align. For the 2026 tax year:

Note that the "quarters" aren't equal — Q2 covers only two months, Q4 covers four. Always pay on the IRS calendar, not the literal calendar quarter.

Federal Safe Harbor Rules

You avoid the federal underpayment penalty if, between withholding and estimates, you pay at least the lesser of:

• 90% of your current-year tax liability, or
• 100% of your prior-year tax liability — 110% if your prior-year adjusted gross income was over $150,000 ($75,000 if married filing separately)

For most growing Colorado Springs businesses, the prior-year safe harbor is the simplest route — pay in the same total you owed last year, split evenly across four quarters, and you're protected even if this year's income jumps. The 90% current-year rule is really only useful if you expect lower income than last year.

Colorado Requirements and Forms

Colorado's estimated tax framework largely parallels federal rules but uses its own forms:

• Individuals (including sole props, partners, S-Corp shareholders): Form DR 0104EP. Required when your Colorado tax will exceed $1,000 after withholding.
• Pass-through entities electing SALT Parity (PTE) tax: Form DR 0106EP — entity-level estimates paid directly by the business.
• C-Corporations: Form DR 0112EP, generally required when expected Colorado tax exceeds $5,000.

Colorado computes underpayment interest on Form DR 0204 at a statutory rate tied to the federal short-term rate. Most Colorado taxpayers satisfy the state safe harbor by paying at least the prior-year Colorado liability, split across the four installments.

Penalties for Underpayment

If you miss a deadline or underpay, the IRS calculates a quarter-by-quarter penalty (Form 2210 for individuals, Form 2220 for corporations), effectively charging interest at the federal short-term rate plus 3 percentage points on each shortfall until it's paid. Colorado applies a parallel calculation on Form DR 0204 (individuals) or DR 0205 (corporations). It's not a flat fee — the charge accumulates per installment, so paying three of four on time still produces a penalty on the one you missed.

Frequently Asked Questions

Do I pay estimated tax on my W-2 salary from my S-Corp?

No. Your W-2 salary has payroll tax and federal/state income tax withheld automatically. Estimated payments cover your K-1 share of pass-through S-Corp income, since that income isn't subject to withholding.

What if my income is uneven throughout the year?

Use the annualized income installment method on Form 2210 Schedule AI to match payments to when income is actually earned. More paperwork, but it prevents overpaying early in a slow year or getting penalized for back-loaded income.

Can I just pay extra with my return to avoid quarterly payments?

No. The IRS and Colorado calculate penalties quarter-by-quarter. Paying the full balance in April for last year doesn't retroactively fix skipped quarters for the current year — the underpayment penalty still applies to each missed deadline.

Staying Penalty-Free Takes a Plan

Estimated tax is straightforward in principle but easy to botch — especially in a growing Colorado business where income is climbing year over year. A CPA who tracks your income trajectory can lock in the right safe-harbor strategy, calibrate quarterly payments to your actual cash flow, and keep underpayment penalties off your books.