Tax Year

DEFINITION of 'Tax Year'

The period of time which is covered by a particular tax return. Many firms simply use the calendar year as their tax year, however this is not always required. When a firm begins or ends operations, it often needs to file a tax return for a shorter time period than a full 12 months. During normal operations, a firm may elect different dates for its tax year in the same way that it may elect different fiscal years. This is typically a simple operation requiring only that certain forms be completed.


Changing the firm's tax year generally does not have any long-term effect on tax liabilities. However, changing the tax year may allow the firm to more efficiently compile the financial information required to complete tax returns. Strategically timing a tax year may also allow for better utilization of accounting resources where preparing the tax return can be made to coincide with a less busy portion of the year.