The HMRC Inheritance Tax toolkit published in April 2020 advises that as "Valuations are the biggest single area of risk, accounting for a large part of HMRC's compliance checks; it is important to properly ascertain the value of assets. For assets with a material value you are strongly advised to instruct a qualified independent valuer, to make sure the valuation is made for the purposes of the relevant legislation, and for houses, land and buildings, it meets Royal Institution of Chartered Surveyors (RICS) or equivalent standards".
Harriet Fleming Surveyors provide RICS compliant Inheritance Tax Valuations. This will include a site inspection, (measurement and photography of the property), detailed comparable research and analysis, a written report and post valuation support including liaising with HMRC, if required.