Sometimes pressure can be brought to bear indirectly. For
example, if you are dealing with an estate outside the United
Kingdom administered by non-resident taxpayers who claim it would
be improper to pay British taxes, they may be encouraged to revise
their opinion if you can identify resident beneficiaries who can be
liable to the extent of the money they receive.
This is regardless of any tax paid by the UK executor ( IHTM05012) whose liability may have been limited by IHTA84/S204. The liability of a resident beneficiary extends to an amount equal to the value of the whole of any traceable foreign property distributed to that beneficiary.
In that context, property means original property or the proceeds of sale that are directly or indirectly representative of the property on which HMRC has a charge.
A further means of bringing pressure to bear on a non-resident taxpayer may be to postpone certification of Inheritance Tax paid in the UK for the purposes of a Double Taxation Convention (DTC) ( IHTM27161).
As most Conventions encourage an exchange of information you should liaise with Technical Group to consider notifying the other Contracting State that there is a payment problem in the United Kingdom. This may encourage the other Contracting State to withhold any tax credit(s) until it has received certification from the UK/IHT that the correct amount of tax has been paid or will be enforced. If, on the same chargeable event, the rates of tax in the other Contracting State are lower than in the UK it is, of course, unlikely that the IHT due will be paid to obtain a credit under a DTC.