If the tenancy is a fixed-term assured shorthold tenancy, the landlord can only change the terms of the tenancy, within the fixed term of the tenancy if the tenant agrees. It is best to agree any changes in writing.
Normally any changes are made by getting the tenant to sign a new tenancy agreement, incorporating the new terms and conditions.
After the fixed term of a tenancy has ended, assured and assured shorthold tenancies will automatically run on as a periodic tenancy, on the same terms and conditions as the preceding fixed-term tenancy. The ‘period’ will normally be either weekly or monthly depending on how rent is paid.
There is also a procedure whereby the landlord or the tenant can propose new terms, including a new rent. This can be done, within a year of a statutory periodic tenancy arising upon the fixed term ending, using a special procedure under the Housing Act 1988. There is a special form, called a section 6 notice, which must be served on the tenant. This procedure may include a change in rent (up or down) but should not be used simply to change the rent alone (for rent only changes, see section 13 notices later). Landlords can obtain the forms from landlord associations, law stationers or solicitors.
Although rarely exercised, the landlord and the tenant both have the right to apply for an independent decision by a rent assessment committee if the new rent cannot be agreed.