Section 32(10) in Kerala General Sales Tax Rules, 1963
(10)Every dealer liable to pay tax shall issue a bill or cash memorandum in respect of every sale involving an amount of Rupee ten or more and in all other cases on demand by the purchaser and where the sale is subjected to approval by the purchaser, such dealer shall issue bill or cash memorandum specifying therein that the sale is subject to approval in a stated period of time.
