Every UK contractor who draws income from their limited company must file a personal self-assessment tax return with HMRC. This is separate from your company's Corporation Tax return and covers your personal income from all sources.
Who needs to file?
You must file a self-assessment return if you are a company director, if you receive dividends, if you have other untaxed income, or if your total income exceeds £100,000. As a contractor operating through a limited company, you will almost certainly meet one or more of these criteria.
Key deadlines
The tax year runs from 6 April to 5 April. Paper returns must be filed by 31 October following the end of the tax year. Online returns must be filed by 31 January. Any tax owed must also be paid by 31 January. For example, for the 2025/26 tax year ending 5 April 2026, your online return is due by 31 January 2027.
What to include
Your return should include your director's salary, all dividends received from your company, any bank interest, pension contributions, and any other income sources. Your accountant will calculate the figures from your company records and prepare the return for you to review and submit.
Payments on account
If your self-assessment tax bill exceeds £1,000, HMRC requires you to make payments on account. These are advance payments towards the following year's tax bill, each equal to half of the previous year's liability. This can create cash flow challenges in your first year of contracting, so plan accordingly.