Presumptive taxation involves the use of indirect means to ascertain tax liability, which differ from the usual rules based on the taxpayer's accounts. The term "presumptive" is used to indicate that there is a legal presumption that the taxpayer's income is no less than the amount resulting from application of the indirect method. As discussed below, this presumption may or may not be rebuttable. The concept covers a wide variety of alternative means of determining the tax base, ranging from methods of reconstructing income based on administrative practice, which can be rebutted by the taxpayer, to true minimum taxes with tax bases specified in legislation.