Csa calculator CSA Payment Calculator Calculate your estimated child maintenance Gross Weekly Income (£) Number of Children 1 Child (12%) 2 Children (16%) 3+ Children (19%) Shared Care (Nights per Week) Under 1 night (No reduction) 1 night (1/7 reduction) 2 nights (2/7 reduction) 3 nights (3/7 reduction) Equal Care (50% reduction) Estimated Weekly Result £0.00