• the complexity of many financial instruments¸ with bewildering new ones appearing all the time
• market volatility¸ yielding gains and losses¸ which may or may not affect the group’s tax liability
• new regimes for taxation of dividends and interest-like returns¸ relief for financing costs and (coming soon) passive income in controlled companies 

• transfer pricing and thin capitalisation rules¸ applying to intra-UK as well as cross-border transactions
• accounting complexity¸ such as hedge accounting and the parallel use of UK GAAP¸ modified UK GAAP and IFRS
• tax law revised (with several later amendments) to accommodate IFRS¸ yielding a number of book/tax differences despite an accounts-based tax regime