Nominating income when paying the RBC

For non-domiciled residents (RND) who have been in the UK for more than 7 out of the 9 previous tax years, using the remittance basis (i.e. choosing to be taxed on UK income only as long as it's not remitted into the UK) has a cost beyond the loss of personal allowances. It's called the remittance basis charge (RBC) and it's currently £30,000 if you have been in the UK for 7 out of the previous 9 tax years or £50,000 if you have been in the UK for 12 out of the previous 14 tax years.

What is less known is that the RBC is actually a tax and therefore if you decide to pay that charge, you also need to nominate the corresponding income. You would think that doing so allows you to bring that taxed income back to the UK without further cost. Unfortunately, HMRC designed the rules so that it becomes impossible to take a credit for the remittance basis charge until and unless all other non-UK income and gains are remitted to the UK. As this is rather unlikely, the RBC is essentially an additional cost of electing to be taxed on the remittance basis.