How long do we guarantee any given tenant for?

Housing Hand guarantees tenants up to 12 months currently, and if they renew, they need to update us so we can renew their application. We guarantee student tenants and working professionals. The tenancy length for a student is typically for a 12-month period and working professional tenants for 6 months-12 months.
   
If a tenant chooses to pay in instalments, we set up subscriptions for either 6 or 12 monthly payments, depending on whether their tenancy is less or more than 6 months in length. If it is less, they will need to pay 6 monthly payments to us and if it falls anywhere between 6 and 12 months long, they will get charged 12 monthly payments regardless of tenancy length.
 
We will contact landlords before the end of the tenancy to check if the tenant will be staying on in the property. We will renew their guarantor policy if they are, but will not cover them if they do not renew.