After the end of its financial year, a private limited company must prepare full annual accounts and submit a company tax return. In most cases, the tax return must be filed within 12 months of the end of the accounting period it covers, and filing must be completed online.

There are penalties for the late submission of company tax returns. The filing penalties will increase for company tax returns where the filing date falls on or after 1 April 2026.

The penalties are designed to encourage companies to file their Corporation Tax returns by the required deadline. Fixed penalties for late filing were originally set in 1998 and have remained unchanged since then. Over time, inflation has significantly reduced the real value of these penalties and therefore their deterrent effect. In real terms, the penalties are now worth roughly half of what they were when first introduced.

The increase in company late filing penalties has seen the doubling of fixed penalties. Since 1 April 2026, a return that is filed late will attract a penalty of £200 instead of £100. If the return is more than three months late, the penalty is now £400, compared with the previous £200. Higher penalties will continue to apply where a company repeatedly files late returns. Where there are three successive failures to file on time, the penalty will be £1,000, and where the return is more than three months late after three consecutive failures, the penalty will be £2,000.

Ensuring that company tax returns are submitted on time will help companies avoid unnecessary penalties and additional compliance costs.