Ex- officio Assessment Mechanism in an Ideal Tax System

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.