TSEM9932 - Ownership and income tax: Specific types of property: bank and building society accounts - joint ownership
When property, including funds in bank or building society accounts, is held jointly, there is a presumption in law that the property is held as joint tenants, but this presumption can be rebutted by evidence (TSEM9230).
In the UK, banks and building societies operate on the presumption of joint tenancy. When informing HMRC of interest credited to account holders, banks and building societies will allocate the interest equally to the persons named on the account on the basis of that presumption. This is an administrative necessity, and is not necessarily indicative of actual beneficial ownership.
If an account is held in the name of ‘A re B’ (usually in the case of a minor - see TSEM9941-9943) it does not signify that the account is held jointly. The account name is not ‘A and B’ but ‘A re B’, which means A in respect of B, that is as nominee or bare trustee for B.