Fixed-term tenancies and rent increases
Question from Trevor updated on 29th October 2009:
Our expert Jeff Montgomery responded:

In general, rent may not be increased during a fixed-term tenancy unless there is a specific clause allowing rent increases in the tenancy agreement. In addition, the rent may only be increased during a fixed-term by giving the correct notice as outlined in section 24 of the Residential Tenancies Act 1986.
If no such clause is included in the tenancy agreement, then a landlord cannot increase the rent during the fixed-term tenancy, except by mutual agreement. Where there is a clause but the tenant has not been given the correct notice, or where there is no such clause and the rent has been increased without the tenant’s consent, the tenant could apply to the Tenancy Tribunal to have the matter resolved. This could include seeking compensation for past rent increases.
If the landlord could show that the tenant did in fact agree to the rent increases, then this could be raised as a defence. The law of estoppel would not appear to be relevant here, but you may wish to seek advice from your local community law centre on this matter. When a fixed-term tenancy ends, the landlord and tenant may negotiate new terms and conditions as part of a new agreement, which may include a new rent amount. To discuss your situation further, you can contact the Department of Building and Housing on 0800 TENANCY (0800 836 262) Monday to Friday, 8am to 5.30pm.
The Department of Building and Housing provides information and guidance on building law and compliance, services including weathertight homes, and advice for tenants and landlords.