A single trade discount is a one-off benefit extended to the buyer when the individual makes a purchase that meets certain conditions to qualify for the discount. The conditions may include bulk purchasing, cash purchasing, or the items might be sold during a sale promotion. For instance, a seller might extend a 20% discount if the buyer purchases $10,000 or more worth of product. Thus, the discount will only come into effect once the total value purchased meets the discount.
A discount series, on the other hand, is a discount provided through a combination of conditions. In such a transaction, the seller extends different discounts once certain conditions are met. For instance, the seller might extend a sale promotion discount of 10% and a bulk purchase discount (100 items) of 20% on the same item. Thus, if a buyer purchases 20 items they will only get the 10% promotion discount, but if they purchase 110 items, they will get both the 10% sale promotion and the bulk purchase discount of 20%. Thus, 10% will first be deducted from the total value and an additional 20% deducted from the remainder.