This Act amends the Child Support Act 1991 and reforms the child support scheme, by providing for a new child support calculation formula, making secondary changes to update the child support scheme more generally, and amending payment, penalty, relief and debt rules for child support.  The new formula accounts for shared care, both parents' income, and estimated average expenditures for raising children in New Zealand.  The particular context of liable parents can also be taken into account.  The Commissioner is given powers to grant a departure from a formula assessment, on specified grounds.