A rental property overseas and you receive rents of 15 and thus declare rental income of 15 but claim expenses of 16 giving a loss of 1 So can you remitt without additional tax, 15 because you declared income of 15 or none because you had a loss? What if you had a small profit?
If the computation is in sterling on UK tax principles and produces a loss (of 1 in your example) any remittance does ot precipitate a UK income tax charge.
You have investments in shares overseas and have capital gains of 15 and capital losses of 10. Can you remitt 15 or only 5? What happens if the losses and gains are in different years, so you have a loss in year one of 10 which you carry forward and then a gain of 15 in year tw
If the sale proceeds from the sale producing the 15 gain and the loss of 10 are made in the same tax year and are credited to the same overseas account any remittance in the same tax year (up to the first 5) precipitates a CGT charge on the net 5. A remittance which occurs in a later tax year precipitates the same tax consequences.
In your second example the capital loss can be carried forward and used to offset the later capital gain; in which case any remittance up to the first 5 is subject to CGT.