This paper explores the dramatic fall in receipts of UK corporation tax (UKCT) from banks, and the widening gap between the global corporation tax recorded as payable in banks' financial statements and the UKCT receipts recorded by the tax authorities. It reviews possible explanations, including changes in tax rates, in operating profits, in deductions which reduce taxable profits, and in the share of profit originating in, or recorded in, overseas jurisdictions. It assigns significant roles to tax-deductible asset impairments and to the allocation of profits among different jurisdictions. It suggests reasons why the recovery in banks' global operating profits may not be accompanied by an early sharp recovery in UKCT receipts.