Flattening behaviour of rough surfaces is studied accounting for inelastic deformation of asperities distributed on the surface. A consistent micromechanical framework is described which includes a rigorous analysis of plastic deformation of a single asperity followed by a micro-macro linking theory relating the local asperity compliance to its global counterpart of nominal pressure and approach distance. The local analysis rests on recent computational advances where results for a wide range of strain-hardening plastic materials have been condensed in concise formulae. An illustration is given where flattening of rough surfaces by normal loading is determined using a statistical topography description and discussed for fractal theory as well.