SETHURAMAN, J.

These three revision petitions have been filed against the order of the Sales Tax Appellate Tribunal (Main Bench), Madras. The assessments relate to 1971-72 to 1973-74. The assessee is a manufacturer and dealer in ultramarine blue. The assessee paid "discount" described as "quantity discount" under a scheme subject to periodical variations. It is stated that the quantity discount is allowed on the basis of customer's off-take in a specified period. The rate of discount and the quantity to be taken are indicated in the scheme. If the purchases during a half-year period January to June or July to December exceeded, for example, 12 cases of large, medium, small or temple blue or 24 cases of some other items, etc., there will be a discount of 1 per cent and if the sales exceeded certain higher quantities, then the discount was higher. Similarly, if the total purchases by a dealer exceeded Rs. one lakh in a year, 3 per cent discount was allowed and if the turnover exceeded that figure, higher percentages were given. The idea was to see that a customer gets an incentive to place orders and increase the volume of purchases. (The word "incentive" is on the facts t