Essential IRS Forms and Due Dates Quick Reference Guide

Income Tax: Form 1040

The most common tax form is Form 1040, the individual income tax return. This is what sole proprietors, freelancers, employees, and most individual taxpayers file. The deadline follows a simple formula: it is due on the 15th day of the 4th month after your tax year ends. Since most taxpayers use the calendar year (ending December 31), this means April 15 of the following year.

Self-Employment and Estimated Taxes

Self-employed individuals owe both income tax and self-employment tax (Social Security and Medicare contributions). Self-employment tax is reported on Schedule SE and filed with your Form 1040 — not separately. If you expect to owe more than $1,000 in taxes for the year, you must also make quarterly estimated tax payments using Form 1040-ES. These quarterly payments are due on April 15, June 15, September 15, and January 15 of the following year.

Business Entity Returns

Partnerships file Form 1065 and S-Corporations file Form 1120-S. Both are due on the 15th day of the 3rd month after the tax year ends (March 15 for calendar-year entities). C-Corporations file Form 1120, due on the 15th day of the 4th month (April 15 for calendar-year entities).

Employers must file Form 941 quarterly for payroll tax reporting. If your business has employees, you are responsible for withholding and reporting Social Security, Medicare, and income tax withholding.