If it is not necessary to obtain possession a landlord may wish to make a claim under the terms of the tenancy agreement for debt using the small claims procedure of the County Court. The amount awarded by the court will be determined at the date of trial. If a claim is being made for interest to be paid on the arrears this must be stated on the claim form because interest will not be added to the debt automatically. If the sum is cleared and then further arrears arise it will be necessary to submit a further claim. The court service has a simple form (N1) that can be completed at the local court or using money claim online https://www.moneyclaim.gov.uk/web/mcol/welcome. The claim fees are based upon the amount of debt due at the date of the claim. Following an application to the court a claimant and defendant may be invited to reach an agreement to settle by negotiation or by using a free telephone mediation service.
It is always worth making an effort to establish any reason for non-payment of rent before taking action. Non-payment may be a result of delays by the local authority in processing a housing allowance claim, and liaison with the tenant and local authority may well be sufficient to resolve any problem.
If the amount of the arrears (and any other charges) is less than the tenancy deposit, it may be worth applying for the case to be adjudicated in accordance with the tenancy deposit protection scheme. Make sure that good paperwork is submitted to support the claim to the adjudicator. Simply declaring on the application form that the tenant did not make a payment will not usually be sufficient.