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HMRC internal manual

VAT Finance Manual

Money (including transfer of money) and related services: securities for money, credit guarantees and related services: liability and value

The provision of either a security for money or a credit guarantee for a consideration is exempt.

The value of the supply for VAT purposes is the total price paid for the service of providing the guarantee or, if it is transferred, the total price paid for it i.e. it is not the value of the amount secured or guaranteed.