Boundary regularity for degenerate and singular parabolic equations

We characterise regular boundary points of the parabolic p-Laplacian in terms of a family of barriers, both when p>2 and p\in(1,2). Due to the fact that p\not=2, it turns out that one can multiply the p-Laplace operator by a positive constant, without affecting the regularity of a boundary point. By constructing suitable families of barriers, we give some simple geometric conditions that ensure the regularity of boundary points.