Basic principles: what constitutes a valid marriage?
For the purposes of Inheritance Tax the term ‘spouse’ applies only to the parties of a legal marriage. The case of Holland (Executor of Holland deceased) v IRC SPC 350 confirmed this. For a marriage that takes place in the UK to be legally recognised, it must conform to the requirements of the law in the appropriate part of the UK.
This requirement applies where a marriage is conducted in the UK according to another faith in, say, a mosque or temple. The couple will be married in accordance with that faith or custom and so long as the requirements of UK law are also met, their marriage will be a legal marriage under UK law. So, the couple will be ’spouses’ for Inheritance Tax purposes and will be able to transfer any unused nil rate band. But, if the requirements of UK law are not met, the couple will not be ’spouses’ and will not be able to transfer unused nil rate band.
Where a marriage ceremony has been conducted abroad, it must meet the requirements of a valid marriage according to the law in the country in which the marriage was celebrated for the parties to the marriage to be regarded as ’spouses’ for transferable nil rate band (TNRB) purposes. If the law of the overseas country permits a polygamous marriage, unused nil rate band from each spouse can be transferred to the survivor, subject to the statutory limitation (IHTM43031).
Similarly, a civil partnership in the UK must be registered according to the requirements of UK law in order to be recognised for TNRB purposes.
There is a type of marriage recognised in Scots Law being marriage by cohabitation and repute (IHTM11032). If, on the first death, exemption under IHTA84/S18 has been granted, the survivor will meet the initial condition in IHTA84/S8A(1)(a) and any unused nil rate band will be available to transfer. Any case where TNRB is claimed on these grounds should be referred to Technical in Edinburgh.
Full details of the legal requirements for a marriage in the UK may be found at https://www.gov.uk/marriages-civil-partnerships/overview