Ok so according to cimarex, they do NOT withhold state taxes if you live IN the state, but they do if you live out if the state. I live in Nm and my brother lives in Co. His check was $200 less than mine, and according to Cimarex, that’s because:
That is New Mexico State Withholding. Since you do not reside in the state of New Mexico where the well is located, by law we have to withhold state taxes. You will have to file state taxes in 2021 in order to get the money back. The state withholding amount will appear on the 1099 when those are sent out at the end of January 2021. Since your sister resides in NM no state taxes are withheld.
This also indicates that there IS a standard set tax that NM has on mineral royalties, regardless of total income (since they obviously have no idea what my brother’s income is). This was actually my original question. From what I can tell, it’s about 5.75 %