IHTM30502 | Remissions: distinction between remissions and irrecoverable assessments
From HM Revenue & Customs · Inheritance Tax Manual
In specified circumstances a claim for tax may be discharged:
as irrecoverable or
by way of remission of tax prima facie recoverable.
The distinction between these two categories is that:
tax which is remitted - i.e. is forgiven - is prima facie recoverable but for special reasons the claim is not enforced
but tax may in whole or part be irrecoverable, e.g. where the liable person (IHTM30011) has disappeared, has become bankrupt, has removed outside the jurisdiction of the British Courts, or has died leaving no estate. The tax is not forgiven but it cannot be collected.