The multilateral lnstrument implements the BEPS recommendations requiring changes to tax treaties, including preventing abuse. Countries must adopt a principal purpose test (PPT), a simplified limitation of benefits test or negotiate their own detailed limitation of benefits provision. Complex rules detail which provision applies where parties to a bilateral treaty choose different options. The UK intends to opt for the PPT. Recent experience of HMRC’s attitude in relation to DPT and the loan relationship unallowable purpose test, coupled with the approaches of other countries, suggests there will be disputes ahead. Structures which are ‘too good to be true’ will be particularly affected.