This paper sets out a new budget allocation formula for schools, designed to achieve a more equitable distribution of educational achievement. In addition to needs-based elements, the suggested composite allocation formula includes an improvement component, whereby schools receive budgetary allocations based on a new incentive measure developed in this paper (Improvement in the Educational Achievement Distribution, or IEAD). The development of the budget allocation formula is demonstrated utilizing Israeli data. Large scale, nationwide data sets relating students’ academic achievement to student background variables, teacher profiles and school characteristics, were analyzed to identify appropriate needs-based formula components and to estimate their weights. The results are compared with the funding formulas currently used in Israel.