Small Business Tax Dictionary
Tax Year
A tax year is a specific 12-month period for which taxes are calculated and reported. This timeframe can follow either the calendar year or an alternative fiscal schedule depending on business needs and jurisdiction requirements.
Tax years by jurisdiction
New Zealand — The NZ tax year runs from 1 April to 31 March. Income, deductions, and other tax matters are assessed over this period, with returns typically due by 7 July (or later if filing through a tax agent).
Australia — The Australian financial year runs from 1 July to 30 June. Tax returns for individuals are typically due by 31 October.
United Kingdom — The UK tax year runs from 6 April to 5 April the following year. Self Assessment tax returns are due by 31 January (online) for the previous tax year.
Why the tax year matters
The tax year serves several critical functions:
- Timing framework — determines when income, deductions, and credits are recognised for tax purposes
- Compliance tool — establishes consistent standards for tax administration and collection across jurisdictions
- Planning baseline — influences overall tax liability calculations and financial strategy decisions
- Comparative analysis — facilitates year-over-year financial comparisons and assessments
Business vs. individual tax years
In some jurisdictions, businesses can elect a different balance date (the end of their accounting year) for tax purposes, which may not align with the standard tax year. This can have implications for when income is recognised and when tax payments are due.
In New Zealand, most businesses use the standard 31 March balance date, but approval can be sought from IRD to use an alternative date.