Mercer urges government and HMRC to clarify GMP equalisation guidance Hartshorn: The government and HMRC need to work together to find a solution to this issue The government must work with HM Revenue and Customs (HMRC) and the wider industry to clarify GMP equalisation uncertainties, Mercer says. In its pre-Budget representation to HM Treasury, the consultancy said there was an urgent need for the government and HMRC to work together to provide trustees with better clarity and the certainty they need to move forward in equalising GMPs. Mercer said one example of an area where clarification was needed was with regards to GMP conversion, where trustees needed assurance the work they had done was valid and without unexpected tax consequences for members.