In The Netherlands, the Centraal Planbureau (Central Planning Bureau, Bureau for Economic Policy Analysis) is an independent government agency that delivers economic analysis of policy plans, among other things. Prior to the elections, all political parties deliver their plans to the CPB. Then the CPB calculates the effects on purchasing power, employment, economic growth, etc. Subsequently, each party cherry-picks the effects that favour their party and use this in campaigning and debates. The CPB also calculates the effects of government plans.
A recent survey has shown that many people have little trust in the forecasts by the CPB, for example, here in Dutch. Perhaps peculiar: the electorate of the small-government party Democraten '66 have the highest trust, whereas the electorate of the pro-welfare state Socialistische Partij have one of the lowest. I consider myself one of those who has little to no trust in their calculations.
Do any analogues of this system exist in other countries? Are there any countries where independent government agencies systematically calculate the economic effects of policy plans by government, opposition, or individual parties, and where those figures are then subject of political debate?