TY - JOUR T1 - Ex- officio Assessment Mechanism in an Ideal Tax System TT - نظام تشخیص علیالرأس در یک نظام آرمانی مالیات JF - Journal-of-Tax-Research JO - Journal-of-Tax-Research VL - 18 IS - 9 UR - http://taxjournal.ir/article-1-113-en.html Y1 - 2011 SP - 9 EP - 24 KW - Optimal Tax Rate KW - Exofficio penalties KW - Tax Evasion KW - Collusion N2 - Tax evasion, collusion and tax avoidance both result in non-realization of the estimated state tax revenue, so developing diverse strategies for preventing these phenomena is the most important tax policies in different countries. One of the states‘ preventive solutions is to encourage and punish taxpayers in different ways. Imposing different penalties for non-compliant taxpayers is the most effective methods and setting effective tax ratio results in increasing tax revenue.By focusing on symmetric tax rate (gross income in an ex–officio and ideal system), this paper aims at preventing tax evasion, calculates the final state revenue gained from a given taxpayer. M3 ER -