This applies to England

Generally if a tenant requests to leave the tenancy before the fixed term it is normally because the tenant’s circumstances have changed and the rent may now not be affordable to them. Rather than creating more stress and rent arrears the tenant may request an early release. The landlord is not obliged to agree to an early release but should consider their options and whether it is worth keeping a tenant tied to a property they can no longer afford, or to re let the property as soon as possible minimising the risk of arrears.

Whilst the Tenant Fees legislation has stopped charging set up and renewal fees for tenants, it does, in England but not Wales, allow for costs to be charged if the tenant wishes to break the contract and leave early.

As there is not normally an early release clause stated in the tenancy agreement, all terms can be negotiated. For example requesting the current tenant pays the rent up until the day before a new suitable tenant moves in, as well as other reasonable costs the landlord may incur through re letting the property earlier then they had anticipated. Example might include advertising the property or arranging for a check out and ingoing inventory and an apportioned amount of management fee for a new tenancy agreement. The landlord should be able to provide an invoice supporting the costs.

When agreeing terms you should do so in writing and include what costs they would be liable for. Any fees quoted must include VAT.

You should keep the current tenant up to date with the progress of any suitable applicants and when the new letting might start, but you should also confirm that if the new tenant does not meet your referencing criteria you would not be able to release the current tenant from the tenancy.