taxYear

A tax year is the annual period used by tax authorities to measure and determine tax liability. It defines the span of time during which income, deductions, credits, and other tax attributes are reported and assessed for tax purposes. The tax year also sets corresponding filing deadlines, payment schedules, and eligibility for refunds or credits.

Across jurisdictions, the length of the tax year and the end date vary. Many countries use the calendar year (January 1 to December 31), but others rely on a fiscal year with a different ending date, such as June 30 or March 31. Some jurisdictions allow individuals or businesses to select or change their tax year, while others fix a single year for all taxpayers. The choice of tax year can affect income timing, deductions, and the calculation of tax liability.

In the United States, individuals typically use the calendar year as their tax year, while corporations may elect a fiscal year. Federal individual tax returns are generally due in April of the following year, with extensions available. In the United Kingdom, the tax year for personal income tax runs from 6 April to 5 April of the following year, and self-assessment or PAYE calculations are keyed to that cycle. Other countries, such as Australia, follow their own fiscal-year structure for official tax reporting.

Understanding the tax year helps align payroll withholding, estimated tax payments, and annual tax filings, especially for individuals with income from multiple sources or cross-border activities.