INTM161240 | UK residents with foreign income or gains: double taxation relief: Measure of income
From HM Revenue & Customs · International Manual
Guidance on how to compute the UK measure of income and on the rules of the limit of credit are found at:
Income Tax - INTM165000 onwards
Corporation Tax - INTM167000 onwards
Tax on Chargeable Gains - INTM169000 onwards
More detailed guidance on trading profits and other income arising abroad is given in INTM163010 onwards.