A quarter is a 3-month period within a fiscal or calendar year. Each year contains exactly 4 quarters, numbered Q1 through Q4 from the year-start month.
Numbering depends on year-start
Quarter numbering shifts with the underlying year definition:
- Calendar year — Q1 January-March, Q2 April-June, Q3 July-September, Q4 October-December.
- Australian financial year — Q1 July-September, Q2 October-December, Q3 January-March, Q4 April-June.
- US federal fiscal year — Q1 October-December, Q2 January-March, Q3 April-June, Q4 July-September.
The same calendar month carries different quarter labels depending on context. October is Q4 of the calendar year, Q2 of the Australian financial year, and Q1 of the US federal fiscal year. A multinational reporting "Q2 results" must specify the underlying calendar.
Common quarterly reporting cadences
Quarters anchor 3 standard business reporting cycles:
- Tax — Australian BAS quarter lodgements; US estimated tax payments; UK VAT returns.
- Public company earnings — ASX-listed entities report half-yearly; US-listed entities report quarterly (10-Q filings).
- Internal management accounts — board packs, sales pipeline reviews, and OKR cycles routinely run on a quarterly cadence.
Quarter-end dates also drive payroll superannuation deadlines in Australia, with employer super guarantee contributions due 28 days after each quarter close per ATO rules.