Check that each assessor is currently registered with SEAI, then compare their total fee, availability, experience with similar homes and what is included in the assessment. Ask whether the price covers the BER certificate and advisory report, and confirm what documents or access they need. It is sensible to obtain more than one written quote, but the cheapest option may not offer the same service or turnaround time. Your final BER rating is based on the property and the assessment, so it cannot be guaranteed in advance; you can verify assessors through the official SEAI website.