Asset Allocation - Choosing best allocation from several options

Hi,

when Before tax Expected Return of various asset allocation alternatives eg A, B, C, D given - and a tax-rate is given, do we
1) calculate after-tax return for each alternative ?
2) then look at return objective for endowment, foundation etc. and then choose the most suitable asset allocation ?

My qs is do we always decide based on AFTER-TAX Exp. Return if given Before-tax Exp. Return ?

Thanks very much
Aaliya