You will usually need property and applicant details, proof of ownership or occupancy, and information about the existing heating system. A registered contractor may arrange a technical assessment and advise whether a heat pump is suitable, while a BER assessment may be needed before and after the works. Keep written quotations, invoices, product details and records of any required electrical or building work. The exact documents and process depend on your home and the grant route, so check the current requirements on the official SEAI website and with your registered contractor; SEAI makes the final decision.