A company accounting reference date is the date in each year to which a company's financial accounts are prepared. This date usually ends at the end of a particular month. The accounting reference date marks the start of the time allowed to deliver accounts to the Registrar of Companies at Companies House.
Every company has an accounting reference date. You have to inform Companies House ahead of any change to the date. Fines and penalties are automatically incurred when incorrect accounts are sent and this results in the correct accounts not being received at Companies House on time. The Registrar of Companies will not accept accounts which relate to a period for which they do not hold on their file.
The month that is initially selected for your company will be the last day of the month in which the anniversary of company formation falls. For example, if the company registration takes place on 25 September, the accounting reference date will be 30 September.