Child support cannot be waived under Nevada law, because it is money that belongs to the child, not to the custodial parent. However, there are a number of factors that can be used to deviate from the normal, statutory percentage of child support. You can find these factors in NRS 125B.080(9). If you are of limited means, and your ex has a vastly superior income, it may be that you can use that factor alone to reduce your child support obligation to zero. Do NOT sign any agreement that says you owe a certain amount of money and then trust a handshake deal from your ex that he "won't collect" what is stated in the papers. That is a serious trap. Once that order is issued, it has no statute of limitations on collections -- he could come back and collect years later, even well after the child is an adult. You have to live by what is in whatever you sign, so make sure you understand it and all terms are crystal clear. Best bet is to take that document to your own attorney for a review.
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Yes, you just need to comply with Fernandez and explain why it isn't going to be paid using a factor set forth in NRS 125B.080. Some example include health insurance costs, travel coats, difference in incomes, etc. Find one that applies and you should be able to get the order signed by the Judge with an amount of child support which is different than would be orders by statute.