Article 59 mandates that the Executive Regulation of the Decree-Law shall define the specific conditions and mechanisms for adjusting Input Tax. This adjustment is required in two primary scenarios involving a change of use before a supply is made. The first case is when Input Tax, initially attributed fully or partially to making Taxable Supplies, is affected by a change in the use of the related goods or services. The second case applies when Input Tax was attributed to making Exempt Supplies or for non-business activities, and the use of the associated goods or services subsequently changed.