I am pretty sure that double taxation is not allowed in the EU, therefore, Nichibei's claim that 20% will be deducted in Portugal because they hold the AOC and then further taxation in the UK doesn't hold water. It is foolish to give tax advice if you are not an EU tax expert and even more so when your source is to quote from several PPRuNe posts! Perhaps I should say it is foolish to accept tax advice given under the above circumstances. There are plenty of web sites that can help one determine their UK tax liability and they calculate both the income tax and the National Insurance contributions, both of which are excluded in the cadet programme's tax relief feature according to OAT.