Utah New Choices Waiver Medicaid taxes

My mother is on the New Choices Waiver in Utah. Since she gets her full gross amount as required by the NCW and doesn't get taxes taken out of it and the majority of those funds is used to spend down monthly, I am told she shouldn't have to pay taxes, but I don't know how to get it to zero. She is in a long-term care facility and the state takes a certain amount, and she pays the facility a certain amount, which is almost her entire monthly annuity and social security. The state says she should not owe federal or state taxes, but no one wants to show me how it's done.