How to File Your Self Assessment Tax Return

The online filing deadline is 31 January following the end of the tax year. For the 2024/25 tax year (ending 5 April 2025), you must file online by 31 January 2026. Paper returns have an earlier deadline of 31 October. Payment is also due by 31 January.

Yes, most company directors need to file a Self Assessment return, especially if they receive dividends or have income over £100,000. HMRC will issue a notice to file if they believe you owe tax. Even if all your tax is collected through PAYE, a return may still be required.

An automatic £100 penalty applies if you are even one day late. After 3 months, daily penalties of £10 per day begin (up to 90 days). After 6 months, a further 5% of the tax due is added. Interest accrues on all outstanding amounts from the deadline date.

Yes, you can file your own Self Assessment return through HMRC's online portal. You will need your UTR number, National Insurance number, details of all income sources, and records of any expenses or reliefs you are claiming. The process typically takes 1-3 hours.

If your Self Assessment tax bill is over £1,000, HMRC requires payments on account. These are two advance payments, each 50% of your previous year's tax bill, due on 31 January and 31 July. You can apply to reduce payments on account if your income has dropped.