When you first arrive in the UK to live as an expatriate you need to consider if you expected to complete a UK tax return.
The UK has differing tax reporting rules for different tax residency statuses so it is only possible to answer when your particular tax residency status can be considered and the different sources of income you may have.
Most typically, people arriving in the UK do so for employment that lasts for less than 2 UK tax years.
During this time you are treated as UK tax resident from the day that you arrive to the day that you leave. This means that you are expected to pay tax on your earnings from the UK and should complete a UK tax return to ensure your tax status is claimed and reported.
If you also have other income such as income from savings and investments outside the UK then you have a choice to either declare this income as normal but with tax relief for the taxes you may have already paid outside the UK, or to choose not to remit the income and leave it accumulating in an account outside the UK. This second option is called the 'remittance basis' and is only available to people who are 'not domiciled' in the UK or considered 'not ordinarily' resident in the UK. But claiming this 'remittance basis' means you are no longer entitled to UK tax free personal allowances.
These are both situations that are potentially complicated so you need to take advice to ensure these options are available to you and which is the most tax beneficial to you.
If you come to live in the UK permanently and you expect to stay for more than 3 years you will become both 'UK resident' and 'UK ordinarily resident' from the date that you arrive and so you will be expected to declare your income from worldwide sources. This normally means that you will need to complete a UK tax return to ensure that the correct amount of tax is paid.
If however you come to the UK and your only income source is from an employment in the UK and you do not pay higher rate tax then you probably do not need to complete a UK tax return each year.
However, any tax year where you leave one country and join another country presents possible tax saving opportunities and pitfalls so you should take advice to help ensure opportunities are not missed.
