The Defence Price Index (FPI) is used to compensate the Swedish Armed Forces for price and wage changes. FPI is based on civil, non-defence-specific, proxy indices representing the Armed Forces' actual wage and price development. In this report, it is argued that FPI does not show compliance with actual price and wage changes. The consequence of this lack of compliance has often been that actual price changes have been undercompensated. The report recommends that a review of the FPI should be conducted. The investigation should also study alternative models to determine the defence appropriations apart from the current model with a, by civilian indexes, defined recalculation of next year's budget. Recently the Government decided that to start an investigation of FPI. The investigation is, though, restricted only to defence equipment whereas earlier reports from FOI have recommended a full investigation. The report can be seen as a preliminary work for an upcoming investigation. The report describes the current FPI, its role and application. Criteria for the design of the price and salary compensation and the selection of the index for this are presented where compliance is highlighted as the most important criterion. One conclusion is that it is difficult to capture the Armed Forces' specific and unique economic conditions with civil, non-defense-specific, indices. Other principal models for making decisions on defence appropriations and compensation for price and salary changes are discussed. It is of great importance that the interface between the decisions on defence appropriations and the price and salary compensation is clarified. It is also important to expand the elements of analysis and follow-up in this decision-making process.