A document published by the Internal Revenue Service that provides the dates on which tax forms and tax payments are due. IRS Publication 509 covers due dates for both individual taxpayers and employers, as well as which other IRS documents should be examined for further information.

The IRS divides the 12-month calendar into quarters and requires some tax payments (for example, estimated individual taxes) to be made each quarter. While most important tax dates are covered in the document, due dates for certain tax types, such as estate, gift and trust taxes, are not included. Additionally, due dates for excise taxes are not provided, but rather can be found in IRS Publication 510: Excise Taxes.