What are the four quarterly estimated tax deadlines?

For the 2026 tax year, estimated tax payments are due April 15, 2026, June 15, 2026, September 15, 2026, and January 15, 2027. The periods are uneven — the first covers three months, the second two, the third three, and the fourth four — so the June and January payments come faster than a strict quarter would suggest.

When are W-2s and 1099-NECs due?

Both are due January 31 — you must furnish the recipient copy and file with the SSA (for W-2s) or the IRS (for 1099-NECs) by that same date. If you file 10 or more information returns in total across all form types, you must file them electronically.

Do I pay estimated taxes if my business is an S-corp or C-corp?

An S-corp itself generally files Form 1120-S and passes income to owners, who pay estimated tax personally. A C-corp pays its own corporate estimated tax on Form 1120-W-style installments, due the 15th of the 4th, 6th, 9th, and 12th months of its tax year. The owner's individual estimates are separate from the entity's.

What is the safe harbor that avoids an underpayment penalty?

You generally avoid the estimated-tax penalty if you pay at least 90% of the current year's tax or 100% of last year's tax through withholding and estimates. That prior-year figure rises to 110% if your adjusted gross income exceeded $150,000. Meeting the safe harbor protects you even if you end up owing more at filing.

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Tax Compliance

The Small-Business Tax Compliance Calendar: A Month-by-Month Guide

Federal tax compliance for a small business is a year-round cadence, not an April event. Here's the month-by-month calendar of estimates, payroll deposits, and information returns that keeps you penalty-free.

SMAART Tax Team

February 10, 2026

6 min read