Landlords who have common law tenancies which will become ASTs on 1 October and whose tenants are in arrears of rent should act now.
Once those tenancies become ASTs the tenant will need to be in 2 months of arrears before the landlord stands a good chance of securing possession in Court. If proceedings are issued before the tenancy converts then it will not become an AST, even if the Court hearing is after 1 October, and the landlord will be able to seek possession under the common law rules of forfeiture. These require the Court to award possession however small the level of rent arrears. While the tenant has the option of paying the outstanding rent and staying in the property he will also be obliged to pay the landlord full interest and their legal costs so the tenant has an incentive to pay up and the landlord does not lose out.
By contrast if the landlord waits until after 1 October he will need to wait for a full two months worth of rent arrears to accrue, give 14 days notice under section 8 of the Housing Act 1988 and then start proceedings. In Court he will get an order for the arrears, interest, but probably less than his total legal costs but the tenant has no right to stay if they pay the landlord. Therefore the incentive on the part of the tenant to pay the debt is much reduced.
However, proceedings must be issued by the Court before 1 October. In practice this means they will need to have been sent to the Court by 27 September at the very latest.