CFM91320 | Debt cap: introduction to allocating the disallowance and exemption: time limit
From HM Revenue & Customs · Corporate Finance Manual
This guidance applies to worldwide group periods of account ending before or straddling 1 April 2017.
The deadline for statements of allocation
Whether the statement of allocation is for disallowances or for exemptions, the deadline for submitting the statement is within 12 months of the end of the relevant period of account. The relevant period of account is the period of account of the worldwide group.