Two-part tariff

A two-part tariff (TPT) is a form of price discrimination wherein the price of a product or service is composed of two parts – a lump-sum fee as well as a per-unit charge. In general, such a pricing technique only occurs in partially or fully monopolistic markets. It is designed to enable the firm to capture more consumer surplus than it otherwise would in a non-discriminating pricing environment. Two-part tariffs may also exist in competitive markets when consumers are uncertain about their ultimate demand. Health club consumers, for example, may be uncertain about their level of future commitment to an exercise regimen. Two-part tariffs are easy to implement when connection or entrance fees (first part) can be charged along with a price per unit consumed (second part).

Depending on the homogeneity of demand, the lump-sum fee charged varies, but the rational firm will set the per unit charge above or equal to the marginal cost of production, and below or equal to the price the firm would charge in a perfect monopoly. Under competition the per-unit price is set below marginal cost.

An important element to remember concerning two-part tariffs is that the product or service offered by the firm must be identical to all consumers, hence, price charged may vary, but not due to different costs borne by the firm, as this would imply a differentiated product. Thus, while credit cards which charge an annual fee plus a per-transaction fee is a good example of a two-part tariff, a fixed fee charged by a car rental company in addition to a per-kilometer fuel fee is not so good, because the fixed fee may reflect fixed costs such as registration and insurance which the firm must recoup in this manner.