The Complete Guide to UK Company Accounts — What Must Be Filed and When (2026)

UK Ltd companies must file: (1) Annual Accounts at Companies House — micro-entity, small, medium, or full accounts depending on size; (2) Corporation Tax return (CT600) with HMRC — includes full accounts. Deadlines: Companies House accounts within 9 months of year-end (private companies); CT600 within 12 months; CT payment 9 months + 1 day after year-end. Penalties for late Companies House filing start at £150 and double if consistently late.