Generally, the last day of the month in which the anniversary of the company's incorporation falls, but this this can be altered (sections 391 and 392 Companies Act 2006). A company's financial years are determined by reference to its ARD. Companies can make up their accounts to the ARD or a date up to seven days either side of it (section 390, Companies Act 2006).

For further details, see Practice note, Company accounts and reports: overview.