The Michigan Cover Sheet For Amendments is a form required by the Michigan Department of Treasury in order to amend a prior year Michigan tax return. This form is used to inform the Department of any changes the filer has made to their original Michigan tax return. It is important to note that this form does not constitute the return itself. There are two types of Michigan Cover Sheet For Amendments: 1. Michigan Cover Sheet For Amended returns (Form 4644): This form is used to amend a Michigan income tax return from the current year or prior years. It is used to report changes to income, deductions, credits, or filing status. 2. Michigan Cover Sheet For Amended Business Returns (Form 4644B): This form is used to amend a Michigan business tax return from the current year or prior years. It is used to report changes to business income, deductions, credits, or filing status.