Ask your landlord or letting agent for an itemised explanation, evidence such as invoices or photographs, and confirmation of which deposit protection scheme holds the money. If you cannot agree, you can usually use the scheme’s free dispute-resolution service, provided the deposit was protected there; the process and deadlines vary across England, Wales, Scotland and Northern Ireland. Keep your tenancy agreement, check-in and check-out reports, emails and photographs, and respond within any stated time limit. For complex disputes, consider advice from Citizens Advice or a solicitor regulated by the SRA.