TSEM7254 | Deceased persons: tax chargeable - no probate or letters of administration
From HM Revenue & Customs · Trusts, Settlements and Estates Manual
HMRC cannot serve a Notice to file a Trust & Estate tax return, if there are no personal representatives. Internal users only should, Email DMB, Estates & Trusts Office (Mailbox) (DM) for advice when neither probate nor letters of administration (confirmation in Scotland) are taken out within one year of the taxpayer's death, and
the total tax due from the estate is likely to be £1,000 or more, or
the tax due is less than £1,000 but there is reason to believe that this situation has been created to avoid paying the due tax.
If the enquiry is urgent, internal users should contact- DMB, Estates and Trust office mailbox