The original installer is liable for fixing the installation to meet the relevant standards. However, the National Audit Office reported that not all installers are complying with the remediation process.38 We asked TrustMark whether the process for installer businesses to become TrustMark-registered (and therefore be able to do work under government retrofit schemes) includes an assessment of the liquidity and financial 32 Qq 70, 71, 137 33 Qq 137, 138 34 Letter from TrustMark, dated 25 November 2025 35 Qq 139 - 142; C&AG’s Report, para 2.14 36 Qq 140, 141 37 Qq 141, 142 38 C&AG’s Report, paras 2.19 and 2.25 14 stability of installer businesses. TrustMark told us that it does not do a “full dive” into the liquidity and stability of a business, but that in most cases a business must have been trading for at least six months before it can be registered for a given area of work.39