Even if your tenant does not fully pass referencing, Rent Guarantee Insurance may still be available for their tenancy.
As long as tenants pass both ID and credit checks, then their application can become eligible with UK-based guarantor(s) who pass referencing and can afford the full rent share of the tenant(s) they are guaranteeing.
Failing credit checks results in the application not being eligible for RGI, even if a guarantor is present.
For tenancies with multiple tenants, every tenant's share of the rent will need to be covered either by a tenant or guarantor(s) who passed referencing.
Multiple guarantors can be added to the application to cover any shortfalls in rent share affordability.
Where there is only one tenant then the guarantor must be able to cover the entire monthly rental amount.
You can purchase guarantor referencing here.
If the tenant is unable to provide a UK-based guarantor, RGI will not be available for your tenancy.
You can find more information how to proceed when a tenant has failed referencing here:
Can I let to a tenant who fails referencing?