Combining theoretical and experimental methods, we investigate the influence of group V fluxes of As-2 and Sb-2 on the InAs(001) surface. We find that equilibrated surfaces under As-2 flux change their surface stoichiometry continuously for InAs in the technologically relevant alpha2 (2 X 4) - beta2 (2 X 4) reconstruction re-ion and that the As-dimer density increases with increasing As-2 flux. The change of the surface morphology under Sb-2 exposure is also studied and discussed specifically in the context of interface formation. The existence of a common alpha2 (2 X 4) reconstruction allows for the possibility of keeping the In sublattice unchanged when switching from As-2 to Sb-2 flux.