Self assessment
Self assessment is the system through which individuals report income HMRC has not already taxed, including dividends from your own company. The online deadline is 31 January after the end of the tax year, with tax payable on the same date.
Also known as: personal tax return, SA100
How it works
A company director who takes dividends normally needs a return, because dividend tax is not deducted at source. You will also need one if you have rental income, self-employment, significant savings income, capital gains, income over £150,000 or a high income child benefit charge.
The tax year runs to 5 April. Paper returns are due by 31 October, online returns by 31 January, and any tax for the year is payable by that same 31 January — alongside the first payment on account for the next year where the liability exceeds £1,000.
Penalties are fixed and unforgiving: £100 the day after the deadline even if no tax is due, daily penalties of £10 after three months up to £900, then further penalties at six and twelve months, plus separate late payment penalties at 30 days, six months and twelve months and interest throughout.
For a director the return is largely a reconciliation exercise. Salary comes from the P60, dividends from the company's records and vouchers, benefits from the P11D. Where the company's bookkeeping is clean, the personal return takes very little time; where it is not, the return is where the problems surface.
Who this affects
- Directors taking dividends above the £500 dividend allowance
- Landlords and anyone with untaxed income alongside a salary
- Higher earners facing the personal allowance taper or the child benefit charge
- Anyone with capital gains to report, including on selling company shares
Common mistakes
- Assuming no return is needed because PAYE covered the salary
- Missing dividend vouchers and estimating the figure
- Forgetting the payment on account due on the same date
- Registering for self assessment too late to get a UTR before the deadline
Frequently asked questions
Do company directors have to file a tax return?
There is no automatic requirement simply for being a director, but most directors do need one because they take dividends or have other untaxed income.
When is the self assessment deadline?
31 January after the tax year ends for online returns and payment, or 31 October for paper returns.
What is the penalty for filing late?
£100 immediately, then daily penalties after three months, and further penalties at six and twelve months, with separate penalties and interest on late payment.
How do I register?
Register with HMRC for self assessment, which issues a Unique Taxpayer Reference. Allow several weeks, as the reference arrives by post.
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Reviewed by Waqas Sagar ACA FCCA FMAAT · Last reviewed 13 September 2026 · Figures for 2026/27 · About our practice
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