25.Section 13 provides that the Scottish Ministers may specify by order what the standard rate for Scottish Landfill Tax is and that they may also make orders to specify which material may be charged at a lower rate; these materials are referred to as “qualifying material”. The lower rate may also be specified by the Scottish Ministers by order. Both standard rate material and qualifying material are charged on a per tonne basis, and a proportionate amount for any additional part of a tonne or if less than one tonne is disposed of. The Scottish Ministers must set the criteria for determining qualifying material and review, revise and publish them from time to time. This ensures that the system for defining the rates of tax and qualifying material is flexible, adaptable and kept up to date.