Rule 12C-1.013, F.A.C. (Adjusted Federal Income Defined), currently reflects the provisions of Section 220.13(1)(a)1., F.S., which requires an addition to federal taxable income equal to the amount of any tax upon or measured by income for Florida corporate income tax purposes. Subsection (5) of the rule provides that value-added taxes are not required to be added back to federal income for purposes of computing the Florida corporate income tax. The Michigan single business tax is included as an example of a value-added tax. On January 1, 2008, Michigan replaced its single business tax with a business tax based on income. The purpose of the proposed amendments to Rule 12C-1.013, F.S., is to remove provisions regarding the now obsolete Michigan single business tax.