JW Corbett is a Wild Life Management Area (Hunting) yes you need a Management Area stamp or pay self service area in the entrance. It is basically a steel post with a slit to drop in the envelope with $3 or $6. You get the envelope at the same location. $3 per person or $6 per vehicle.
They have added many rules which is why I don't go there too often these days. Trail #6 is one that is open all year. It can be totally impassable during rainy season and in dry season the entire trail is sugar sand which it is lots of fun.