IHTM45044 | Reduced rate for gifts to charity: elections: late claims
From HM Revenue & Customs · Inheritance Tax Manual
Under IHTA84/Sch1A/Para 9(3), an officer of Revenue & Customs has the discretion to admit a late claim for either an election to merge components () or to opt out of the reduced rate (). The circumstances in which you may admit a late claim are the same as for a late claim to TNRB and you should follow the guidance at .