With an incident meter you do the same corrections. As both, the incident as the reflective meter, are based on a 18% reflective surface.

Corrections of this kind are the reason I prefer a meter of the kind of the Gossen Profisix, that enables you to "place" deliberately with no effort the metered result at several stops under and above the standard. (Caution: the Mastersix, though having the same scale does not enable this.)