More detailed guidance: residence outside the UK
There is no requirement that the residence (dwelling-house) has to be in the UK but it does have to be within the scope of IHT and it has to be included in a person’s estate. Whether the residence is within the scope of IHT may depend on the domicile status of the deceased and the location of the property.
For UK domiciled individuals, who are subject to IHT on their worldwide assets, it does not matter where the residence (dwelling-house) which is left to direct descendants is located. For non-UK domiciled individuals, who are subject to IHT only on their assets in the UK, the residence which is to be left to direct descendants must be situated in the UK in order to be within their estate for IHT purposes and hence to be able to qualify for the RNRB.