The latest debate about investing and tax has an added salaciousness because some of the investments concerned are abroad or “offshore”. The first thing to grasp is most overseas investments by UK savers are nothing to do with tax planning, but are undertaken to diversify the person’s investments and obtain income and gains from the success of foreign companies and countries.
Again let’s start with the MPs. The MP Pension Plan has substantial investments in foreign assets, like most company and government funded pension plans. These assets are not bought to save tax. The beneficiaries of the MP Pension Plan are enjoying complete tax relief on all the income and gains whilst the money stays in the fund anyway, so it makes no difference where the holdings are invested. For taxpayers saving money and investing abroad, again there is no tax advantage as long as they declare things honestly. If you buy a foreign investment from UK money outside a Pension Plan or ISA you have to pay full income tax and capital gains in the normal way on income and gains made.
Many UK people own unit trusts or Exchange Traded funds that provide them with ready made portfolios of shares. Many of these are based abroad. Under EU UCITs rules providing a legal framework for such funds most are set up in either Ireland or Luxembourg, two of the EU’s “tax havens”. All this is legal under EU and UK rules. UK holders of units or shares in these funds pay full UK tax on income as they earn it and gains when they take them. It is an interesting sidelight on how good the EU single market is for the City that most of these funds are resident outside the UK.
A minority of overseas arrangements are designed to allow rich people or companies to change tax jurisdictions. These could be tax evasion. The people involved need to take good advice and to declare what they are doing to the relevant authorities. The UK now has a requirement for people to register schemes prior to entering them. Any UK citizen and resident who withdraws a load of cash, takes it out of the country, and then invests it elsewehere without declaring the income and gains to the UK authorities is committing an offence and should traced and prosecuted. There are sophisticated electronic versions of the same thing which are also against the law.