This canon means that the taxpayer should know how much tax he has to pay, the time by when it must be paid and the manner in which the tax must be paid Thus, for example, the amount to be paid in tax should not be an arbitrary or based on discreation of the tax administration or official. This canon is very relevant to date as the protection of taxpayers from unnecessary harassment by the tax authority is a required standard of a good tax system, and also the practise of integrity and zero tolerance for corruption in the tax administration is highly regarded as a vehicle for the efficiency and effectiveness of a tax agency as reflected in many literature on good governance.