Generally a tax should not be considered in isolation. There are areas of VAT law and practice which advisers more familiar with other taxes may find difficult to comprehend. Interaction of VAT with other taxes, duties and levies raises these questions:
(1)is VAT chargeable on the same occasion as another tax; and
(2)is VAT an allowable deduction when computing liability to another tax?
These questions are solved by applying general principles, although statements of practice have been issued by the tax authorities.