It's the County Treasurer office, (and that's who the check is made out to also) NOT the County Commissioner. There's a couple of counties that don't issue for some reason or another but pretty much you can send to any Treasurer, it doesn't have to be in the county you plan to hunt in. Just be sure to select the right WMU though.
As of right now, there are tags remaining in WMU 1A, 2A, 2B, 2D, 3B, 3C, 3D, 4A, and 5 A, B, C D. All other units are sold out.
Dale
