If you are in your first year of trading as a limited company it is likely that your financial year runs slightly longer than 12 months.
If you set up on the 15th of January 2026, for example, your first company year end will default to 31st January 2027.
Unless you set up on the first of the month, it will always go to the end of the month and on one year.
This means that your first financial year is usually 12 months and a number of days. This is not an issue for Companies House where you can file accounts for this period.
However HMRC's systems only allow you to file Corporation Tax returns that cover a period of a maximum of 12 months.
This means that the first year's accounts are split into two, with one period being 12 months and the other being the remaining days.
This will not have an impact on the amount of tax you have to pay, as it is all calculated in the same way, but it will mean you will have to review and sign off two corporation tax returns.
For all following years the Corporation Tax returns should match your financial year and you will only have one Corporation Tax return to review and submit.
