This Practice Note explains the UK’s hybrid rules counteracting deduction/non-inclusion (D/NI) mismatches arising from payments or quasi-payments made under, or in connection with, hybrid financial instruments (chapter 3) and D/NI mismatches arising from payments or quasi-payments as a consequence of a hybrid transfer arrangement (HTA), ie an arrangement (such as a repo or stock loan) relating to the transfer of financial instruments where the arrangement gives rise to a mismatch because either the arrangement is, for different persons, treated differently for tax purposes (the dual treatment condition) or could involve a substitute payment (chapter 4). This Practice Note also discusses the meaning of financial instrument, HTA and qualifying capital amount and qualifying capital tax. This Practice Note was produced in partnership with Dominic Robertson of Slaughter and May.