Concepts
Calendar year
A calendar year runs from 1 January to 31 December. In Australian tax it appears in some contexts, but most obligations run on the 1 July to 30 June financial year.
A calendar year is the familiar period from 1 January to 31 December. In Australia, most tax returns and business income tax are based on the financial year, which ends on 30 June, so the calendar year is not the default period for income tax. However, the calendar year does show up in various tax contexts, and confusing it with the financial year can lead to mistakes in records and reports.
One place it matters is in international dealings. Many other countries use the calendar year as their tax year, so Australian residents with overseas income, and foreign residents with Australian income, often need to translate between periods. Foreign income may be reported by the overseas authority for a calendar year, but you will generally need to work out the amount that falls within the Australian income year.
Some businesses also choose a substituted accounting period ending on 31 December, which aligns their income year with the calendar year. This may suit a business owned by an overseas parent that reports on a calendar basis. Such a choice requires ATO approval and does not alter the BAS cycle, which continues to be based on tax periods, such as calendar months or the standard quarters.
The standard BAS quarters happen to be aligned to calendar quarters: July to September, October to December, January to March and April to June. This sometimes leads people to think of the BAS year as a calendar year, but the quarters are labelled as part of financial years. Monthly BAS also follows calendar months. The key point is that GST reporting is in tax periods, not years, unless you are an annual reporter.
Calendar year thinking also appears in everyday administrative matters. Contracts, subscription periods, insurance policies and leases are often written on calendar-year terms. When a payment covers a period that crosses 30 June, you may need to decide how much relates to each financial year for income tax purposes, particularly for prepaid expenses, and the GST on that payment is generally reported based on your accounting method and tax invoice timing.
A common misunderstanding is expecting bank statements, payroll summaries or sales reports for a calendar year to match a financial year return. They will not align without adjustment. When preparing records, run reports for the correct period and check they start on 1 July and end on 30 June. This is general information only, so confirm which period applies to your situation with the ATO or a registered tax professional.
Worked example
A freelance designer is paid by a US client who sends a summary for the calendar year 1 January to 31 December 2025, totalling $60,000. To prepare her 2025-26 Australian return she needs the income received from 1 July 2025 to 30 June 2026. She uses the client's monthly statements to find that $24,000 was received between January and June 2026, and adds the figures for July to December 2025.
Practical tips
- Run accounting and bank reports for 1 July to 30 June when preparing your return, not for the calendar year.
- If you have overseas income reported on a calendar-year basis, work out which amounts fall in the Australian income year.
- Do not assume BAS quarters follow a calendar-year label. They are tax periods within the financial year.