Quarterly estimated tax deadlines for 2026: dates and planning guide

The IRS payment periods are not four equal calendar quarters. The first period runs January through March, the second April through May, the third June through August, and the fourth September through December. That is why the dates are April, June, September, and January rather than exactly three months apart.

Self-employed people, sole proprietors, partners, and S corporation shareholders often need estimated payments because business income may not have enough tax withheld during the year. C corporations have a separate corporate estimated-tax regime. An owner who also receives wages may sometimes adjust withholding instead of relying only on quarterly payments.

A useful estimated-tax process is not 'set it in April and forget it.' Reforecast after a material profit change, large asset sale, bonus, new business line, or change in withholding. The IRS provides an annualized income installment method for qualifying situations where income is uneven during the year.

Retain confirmation numbers and record each payment in the tax workpapers. At year-end, reconcile the payments made to the amounts reported on the return. Missing estimated-payment records are a common reason a return shows a balance due that the taxpayer believes was already paid.