This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

Corporate Finance Manual

Other tax rules on corporate debt: tax mismatch schemes: Meaning of scheme period

For the purposes of the tax mismatch rules, the ‘scheme period’ includes the whole period during which the scheme has effect. This will include all periods in which the impacts of the scheme are realised beginning with the first act or omission under the scheme and ending with the last.

If the scheme period is uncertain then, in determining whether the scheme is a TMS, any reasonable assumption as the scheme period may be made.