I assume you are a national of the UK, and as such you are entitled to enter, stay and seek employment anywhere within the European Economic Area, which includes the countries you mention. Expatriates of non-EEA countries need a visa and a work permit. Once legally within the EEA, expats of all nationalities tend to be treated by authorities, etc. much the same as nationals of the host country. You will need to enter all the various systems in your chosen country and, unlike in the UK, pretty much everywhere this will first and foremost mean being placed on the residents' (national) register. Through this you will acquire a national identity number and (often) a card. Usually this allows you to do all the official stuff, including opening a bank account, and you will not need to identify yourself in any other way (you will have done it pretty much once and for all). This is particularly true of the Nordic countries, whereas elsewhere it may take a slightly different form. If you expect to reduce your tax burden by going to a Nordic country then you are likely to be seriously disappointed - but there are compensations, both financial and cultural.