As a landlord, you need to remain vigilant; monitor your bank account, and contact the tenant as soon as a payment fails to appear. This not only sends the message that you won’t let late payment slide, but will inform your tenant of an issue in the event that the problem was caused by a bank error instead of them.
If the tenant is going through an unexpected rough patch, you may want to come to an arrangement with them that benefits you both (such as a payment plan, or an offer to leave their lease early). When discussing rent issues with your tenant, always make sure to confirm things in writing to leave a paper trail that can be used as evidence later if (but hopefully not) needed.
If your tenant has provided you with a guarantor, or is in receipt of housing benefit, you will be able to contact these parties for payment instead. Merely contacting them may be enough to see your tenant pay what they owe, or you can begin proceedings to reclaim money from them instead.
If the tenant is troublesome, near the end of their tenancy, or ignores your efforts to contact them, you may want to look at eviction proceedings; the Housing Act 1988 allows you to reclaim possession of your property via Notice to Quit or Notice of Possession (depending on circumstances) after your tenant is 2 months (or eight weeks) in arrears. You will need to follow proper produce during this stage, so it would be wise to seek legal advice at this point.
Even if a tenant is in rent arrears, landlords cannot legally enter the property without permission, change the property’s locks, forcibly remove the tenant or any of their belongings, or take on new tenants for the property in question.
The important thing is to take decisive action, as the sooner you act, the sooner things can get resolved