Alaska How to Calculate Child Support Under Civil Rule 90.3 is a set of guidelines used to determine the amount of child support that should be paid by a noncustodial parent in the state of Alaska. The rule is based on a set of statutory factors that are intended to ensure that the child is provided with a reasonable standard of living and that the noncustodial parent pays their fair share of the cost. The calculation of child support is based on the income of both parents, the number of children, and the parenting arrangement. There are two types of Alaska How to Calculate Child Support Under Civil Rule 90.3: the Flat Percentage Rule and the Income Shares Model. The Flat Percentage Rule divides the noncustodial parent’s monthly income by the total monthly family income and then multiplies that fraction by the total family expenses. The Income Shares Model is a more complex method that takes into account the income of both parents, the number of children, and the parenting arrangement. Both methods are used to determine the amount of child support that should be paid by the noncustodial parent.