Yes, accounts can be prepared under IFRS or UK GAAP. Many companies prepare their group accounts under IFRS, but the Parent company’s accounts under UK GAAP. The main reasons for this are that under IFRS dividends paid up to the parent out of pre-acquisition reserves cannot be paid out as a dividend by the parent (whereas under UK GAAP they could), and the use of fair value accounting under IFRS can result in tax being payable on unrealised profits (whereas under UK GAAP only realised profits are taxable).