Article 55 of the UAE VAT Executive Regulations fixes the Tax year for each Tax Period cycle, sets the method for apportioning Input Tax between supplies that allow recovery and those that do not, requires an annual adjustment, imposes a further adjustment where the difference exceeds AED 250,000, and allows an application to use an alternative apportionment mechanism. Cabinet Decision No. 149 of 2026 amends the apportionment and calculation clauses and adds a mechanism for Government Entities and Charities, which shall come into effect from the first Tax year commencing after 1 October 2027.