Is it necessary to maintain a special accounting system ?

Most businesses will require only minor modifications to their record keeping. In order to complete his VAT return a taxpayer will need to ensure that his books and records provide:
(a) The amount of VAT paid on purchases.
(b) The amount of VAT collected on sales.
(c) A method of distinguishing between taxable and exempt sales.
(d) The time the goods and services were supplied.
(e) Evidences that goods were exported, if any.