Unlike what you might think based on the news, the money in offshore savings accounts is not tax-free. For UK tax purposes, the same personal savings allowance is applied to any savings held in an offshore account, which means that basic rate taxpayers can earn the first £1,000 in savings interest per year without having to worry about taxation.
Anything above this will need to be declared through a self-assessment form with HMRC as income. While this means you would then have to pay some tax, there could be a welcome delay – depending on when you open an account and when the tax year ends – that allows you to add some more savings interest before taxation gets applied.
Remember that you may have to pay tax in the country you are residing in as well, so make sure you have everything sorted out fair and square – you don’t want to get into trouble with any government or pay double tax when you don’t need to. Given the numbers likely involved in all of this, you may even want to get professional advice so you can be sure you’re always declaring and paying the right amount for taxation.