One interpretation of proton stability is that it implies the existence of extra-flat directions of the minimal supersymmetric standard model, in particular ucucdcec and QQQL, where the operators lifting the potential are suppressed by a mass scale Λ which is much larger than the Planck mass, . Using D-term hybrid inflation as an example, we show that such flat directions can serve as the inflaton in supersymmetric inflation models. The resulting model is a minimal version of D-term inflation which requires the smallest number of additional fields. In the case where Q-balls form from the extra-flat direction condensate after inflation, successful Affleck–Dine baryogenesis is possible if the suppression mass scale is . In this case the reheating temperature from Q-ball decay is in the range 3–100 GeV, while observable baryon isocurvature perturbations and non-thermal dark matter are possible. In the case of extra-flat directions with a large t squark component, there is no Q-ball formation and reheating is via conventional condensate decay. In this case the reheating temperature is in the range 1–100 TeV, naturally evading thermal gravitino overproduction while allowing sphaleron erasure of any large B–L asymmetry.