Virginia,
28% ???
Out of state mineral owns are subject to 5% state income tax.
All owners are subject to 7% severance tax. (Although there are provisions for it to be less when prices are very low). However there are some incentives with non-conventional drilling. Usually Horizontals qualify for 6/7 exemption until the well pays out or 4 years (the one occurring 1st)
I've assisted a few out of state owners with Oklahoma production and their stubs reflected 5%.
I have seen 28% held before. But it was federal backup withholding because no W-9 was submitted by the mineral owner.  
 Virginia Pflum said:
In Ok, if you live out of state, they take 28% off the top.