Start by asking the landlord in writing for the deposit’s return and explaining any disagreement about deductions. If it is not resolved, you can apply to the Residential Tenancies Board (RTB) for dispute resolution and provide evidence such as the tenancy agreement, inspection records, photographs, messages and receipts. The RTB may offer mediation, or the case may proceed to adjudication, where both sides can present their information. Any decision depends on the individual tenancy’s facts and the evidence provided, and may be subject to further RTB procedures. Check the current process and time limits on the official RTB website, or seek advice from a solicitor if the amount or circumstances are complex.