The reform of corporate losses by Finance (No 2) Act 2017 included a mixture of relaxations to the use of losses within the previous regime which applied before 1 April 2017 and also a major restriction (50% above a certain limit) on the amount of profits after 1 April 2017 that can be covered by the offset of most losses carried forward, including pre-April 2017 losses.

This guidance note details the options for using trading losses carried forward and the 50% restriction is dealt with in the Carried-forward losses restriction guidance note.

HMRC guidance on the relaxation is at CTM04840 and on the restriction is at CTM04830.