Do I have to include overtime in my GMI when calculating child support?

Maybe.  The Nevada Supreme Court had this to say about the subject: overtime should be included as income, "if it is substantial and can be determined accurately."  Scott v. Scott, 107 Nev. 837, 822 P.2d 654 (1991). For a more complete explanation of the rules for calculating child support, see: http://willicklawgroup.com/child-support/. If that does not answer your questions, schedule a consultation with a family law specialist in this or some other family law firm, and go over your specific facts and circumstances.