It would not be possible to list all of these, but one that has affected expatriates is the Child tax Credit, that is unless they are a State Pensioner.
We were all told that that in 2003 there were to be changes in the way Child Tax Credit was to be paid, so as to ensure that the money, hitherto granted by way of a tax allowance, was to be paid to the main carer directly into their bank account. As many couples have joint bank accounts this objective is not sustainable. Further what we were not told was that it was to be residence based. The only exception being if you are a pensioner, when you then became subject to EU. Regulations.
What our Chancellor did not tell you was that a great many EU. resident expatriates are subject the Double Taxation Treaty U.K./Spain 1975 and are therefore liable to pay income tax in the U.K. on all their U.K. income. They are therefore denied either the former income tax allowance, or the Child Tax Credit, which is available to U.K. Citizens where they have children in full time education up to age nineteen years.