Tax deadline refers to the due date by which tax returns must be filed and taxes owed must be paid to the relevant government authorities, such as the Internal Revenue Service (IRS) in the United States.

The tax deadline can vary depending on the type of taxpayer and the tax year in question. For individual taxpayers in the US, the tax deadline is usually April 15th of each year for federal income tax returns, although it may be extended in certain circumstances.

It is important to file tax returns and pay taxes by the tax deadline in order to avoid penalties and interest charges.