The UK Self Assessment tax system
The UK tax year runs from 6 April to 5 April and tax returns are prepared on an individual basis.
Not every UK resident is required to file a UK tax return. If your circumstances are straightforward, with a UK payroll and small UK investment income, it’s unlikely that you’ll need to file one.
If you or your parents were born outside the UK, it’s possible that you’ll be considered not domiciled in the UK for tax purposes. Domicile essentially means “place of permanent belonging”, so if you have made no definite plans to remain here in the UK for the rest of your life, you’re unlikely to be regarded as UK domiciled.
If you’re not UK-domiciled, you can choose the remittance basis of taxation. This generally means that you are only taxed on your UK source income and gains plus any overseas income and gains you bring into the UK. If you have income which doesn’t have tax withheld at source or wish to claim the remittance basis, you will likely have a UK tax filing requirement.
If a UK tax return is required, you must register for UK Self Assessment by 31 October following the end of the tax year in which you arrive. Your first UK Self Assessment tax return will be due the 31 January following the end of the tax year. If your UK tax returns shows a liability due, this is payable on the same date the return is due.