The United Kingdom (UK) has a complex tax system which enables the UK government to collect taxes from individuals who are also taxed on the same income in another country. This can result in a tremendous tax burden.For example, if the UK taxes certain income of individuals at the highest rate of 45% and the other country does the same, this will result in an effective tax rate of 90%. People who consider leaving the UK will benefit from choosing a country that has a double tax treaty with the United Kingdom. A double tax treaty is a treaty between two countries which includes provisions avoiding the double taxation of legal and natural persons.In our free e-book "Avoid tax as a Brit" we provide a better understanding on how to avoid double taxation, we examine the methods used to determine the existence of dual tax residency in the UK and another country.  Afterwards, we explain how British expats can use double tax treaties to avoid double taxation Next, we discuss four countries that have double tax treaties with the UK which have a good potential for tax optimization purposes.