IHTM40040 | Procedures for dealing with an application for clearance: is a certificate appropriate?

From HM Revenue & Customs · Inheritance Tax Manual

A certificate is appropriate where

there has been a transfer of value (IHTM04024);
the property in question is liable to tax (even though no tax may in fact be payable),
the appropriate account (IHTM10011) has been delivered

You can issue a certificate where

tax would be payable if the minimum taxable threshold were exceeded
a relief covers the tax otherwise chargeable.

You can also issue a certificate where no tax is payable because of exempt gifts

to spouses or civil partners (IHTM11031)
to charities (IHTM11101)
to political parties (IHTM11191)
for national purposes (IHTM11221)
for public benefit (IHTM11224), and where
the estate includes government securities in foreign ownership (IHTM04291) which are exempt under IHTA84/S6 (2).

You cannot issue a certificate where the property is not chargeable to tax at all (IHTM04141), for example because of the surviving spouse exemption (IHTM04341) available under IHTA84/Sch6Para2. You should also not issue certificates for lifetime transfers (IHTM40011) that are chargeable to tax when made unless the person who made the transfer is now dead and full details of the estate have been received.