政府於2001年引入半年結算制度，期望藉由增加預算執行監督頻率，以提高政府單位平時之預算執行率，減輕預算集中於年底執行之情形，進而提升施政成效。爲了瞭解此制度實際之推動情形，本研究以國防部門爲對象，採用1998至2004年資料進行實證分析。研究結果指出，制度實施之第一年，上半年作業維持預算執行落後情形顯著減少，然軍事投資預算執行落後情況並未顯著改善。然而，當擴充觀察期間後，本研究發現此制度對國防部門作業維持預算與軍事投資預算執行均具有顯著之影響，此實證結果顯示，公務預算執行存在著代理問題，而監督頻率的提高，有助於降低此代理問題，進而提高預算執行率。

To reduce high concentration of budget execution at yearends and improve budget execution rate at other times, the government in 2001 initiated the Semi-annual Balance Statement (SBS), which increases monitoring frequency by adding a mid-year review of budget execution. In an attempt to help understand how this system works in practice, we take Defense units as an example and conduct an empirical study using data in the period between 1998 and 2004. Our findings show that the SBS only worked for the Operation and Maintenance (O&M) budget, not for the Military Capital (MC) budget, for the first year of adoption. However, in our extended sample, we find that the SBS had a significant impact on both O&M budget and MC budget execution, indicating that there exists an agency problem in the area of public budget execution. More importantly, our results demonstrate that increase in monitoring frequency can mitigate the agency problem and, thus, produce higher execution rate.