The time period between January 1 and April 15 of each year in which individuals traditionally prepare the previous year's financial statements and reports. In the United States, individuals must file their annual tax return by April 15 of the year following the reportable earnings.

During tax season, businesses must furnish employees, contract laborers and others, such as royalty earners, with tax documents specifying data required to complete individuals' tax returns. People who are required to file a tax return must do so by April 15 or request an extension.

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Tax season is the busy season for many tax preparers and accounting professionals. This three and a half month period is the time that people collect the necessary paperwork, including wage and earnings statements (such as 1099s or W-2s) and assemble tax returns.

While some individuals calculate their own tax returns, many rely on the expertise of tax preparers and accounting professionals to be certain the paperwork is filed correctly and to improve the financial outcome of the tax return. Individuals must file federal, state and, in some cases, local tax returns.