What is the 91-day rule?
Tax Residency
The 91 day rule forms part of the test governing tax residency in the UK and it works in conjuction with the 183-day rule.
From April 2008, when deciding if an individual is resident in the UK for tax purposes, days will count if you are in the UK at the end of the day (i.e. at midnight) for residence test purposes.
A person who is currently not resident in the UK will always be treated as resident in the UK if they spend 183 days or more in the UK in any tax year. If they visit the UK on a regular basis and spend, on average, 91 days or more in the UK in a tax year (taken over a period of four years), they will be treated as resident in the UK.
If they know that they are going to visit regularly and that the time spent in the UK in that and the next three tax years will average 91 days or more in the UK, they will be resident from the beginning of the tax year in which they make the first visit.
If they have been resident in the UK and, having left the UK, continue to visit, they will continue to be treated as resident if those visits average 91 days or more a tax year, taken over a maximum period of four years.
Therefore if you leave the UK for work overseas, remain out of the UK for one complete tax year and during the period your trips back to the UK are not more than 91 days (midnight rule applies), averaged over a four year period, you will become non tax-resident.
For more information on the subject of gaining and losing tax residency see our Tax Residency FAQs or follow the link to useful UK tax forms.