The new corporate interest restriction (CIR) regime, which is expected to be enacted retrospectively with effect from 1 April 2017, represents a significant restriction on groups’ ability to obtain UK tax relief for finance costs. It also poses significant practical challenges for UK groups, including in terms of: determining the scope of the CIR worldwide group; gathering and ‘cleansing’ all the data required in order to perform CIR calculations; making strategic decisions regarding elections, allocations and restructurings; and determining the impact on financial statements and tax instalments.