Providing Adequate Resources to Enhance Needed Time with Sons and daughters Act of 2021 or the PARENTS Act of 2021 This bill expands the use of federal incentive payments to states under the Child Support Enforcement Program to include establishing agreements for how much time a child spends with each parent as agreed to by the parents under a child support or medical support order. Generally, the incentive payments program provides funding based on a state's performance measures related to (1) establishing paternity, (2) the number of cases with child support orders in place, (3) the collection of current and past-due support payments, and (4) cost-effectiveness.