Throughout the history of publicly-funded voucher programs--enacted and proposed--the impact on taxpayers has been a recurring issue. As the nation's longest-running program, the Milwaukee Parent Choice Program (MPCP) provides an important case study. The fiscal impact of Milwaukee's program has evolved in very significant ways over its 18-year history, both in size, as the program grew, and in its allocation among different groups of taxpayers--Milwaukee property taxpayers, non-Milwaukee property taxpayers, and Wisconsin state taxpayers. This report closely examines the features of the MPCP funding formula, and its interaction with the state's regular district funding formula over the program's history to better understand the impact on taxpayers. The fiscal impact of vouchers can be broken down into two distinct questions: (i) the amount of public funds potentially freed up by the transfer of students from district schools to voucher schools; and (ii) the allocation of those funds among various taxpayers by the funding formulas. With regard to the first question, the MPCP has long featured a voucher that is significantly below the per pupil revenues in the Milwaukee Public Schools (MPS). This difference provides significant potential taxpayer savings, much like those that would be generated by voluntary enrollment shifts from high-spending to low-spending districts. The magnitude of these potential savings depends on the enrollments, and the number of voucher-users who would have attended MPS in their absence. These variables are examined in the first part of this report to estimate the net impact of the MPCP over the life of the program, compared to likely scenarios had the MPCP never existed. The size of the net impact is somewhat sensitive to assumptions, but for most likely scenarios the net impact is positive taxpayer savings. The second part of this report provides an analytical dissection of the funding formulas over the life of the MPCP, to help estimate and understand the allocation of the MPCP's net impact among the various classes of taxpayers. This analysis explains why the funding formula changes adopted thus far have not eliminated the problem. Concluding remarks suggest possible lessons from the MPCP funding history. Three appendices are included: (1) Review of Selected Previous Literature; (2) Further Details in Funding Formulas; and (3) Equations Underlying Tables and Figures. (Contains 9 figures, 8 tables and 66 footnotes.) [For "The Comprehensive Longitudinal Evaluation of the Milwaukee Parental Choice Program: Summary of Baseline Reports. SCDP Milwaukee Evaluation Report #1", see ED508631.]