Matondang E Siburian ndonesian Ministry of Finance - Directorate of Taxes   Kantor Pusat Direktorat Jenderal Pajak Jalan, Jend. Gatot Subroto No.40-42 Gedung MM Lt.26 Jakarta, Jakarta 12190 Indonesia   mes1701@fuji.waseda.jp             JEL Areas: H : Public Economics C0 : Mathematical and Quantitative Methods: General