AP MicroeconomicsMicroeconomic Theory
Two-Part Tariff
A two-part tariff is a pricing scheme with a fixed entry/access fee plus a separate per-unit price, used to capture consumer surplus beyond a single uniform price.
A firm with market power charges a lump-sum fee for the right to buy (the membership or access charge) and then a per-unit price for each item consumed. With identical consumers, the firm can set the per-unit price equal to marginal cost (the efficient quantity) and set the access fee equal to the consumer surplus, extracting nearly all the surplus while still producing the efficient output. Real examples include amusement parks (entry + per-ride), warehouse clubs (membership + prices), and phone plans (line fee + usage).
Formula / Example
Total charge = Fixed fee (A) + (per-unit price × quantity); optimal with identical buyers: per-unit price = MC, A = consumer surplus.