UK & French tax residency rules are different. If you are a UK or French citizen and are considering or have already moved from one country to go and live, work, study or retire, in the other country, even temporarily, the question of tax residence becomes crucial.
Why is it important to be sure of your tax residence?
Put simply, without establishing your tax residence you cannot be sure whether you are paying the right amount of tax in the right country. But because the rules for determining tax residence differ from country to country it can become complex to correctly determine your tax residence.
To make matters a bit more complicated, it is entirely possible to be a tax resident of more than one country.