Fee or free? How much to add on for an add-on

Sellers often provide complimentary "no extra charge" add-ons (e.g., free Internet connection) to consumers who buy their primary products (e.g., a hotel stay), but recently add-ons that used to be free are offered for a fee. The conventional wisdom is that unadvertised add-ons for high fees help competitors increase profits that are competed away by advertising low prices for the basic products. This theory cannot explain why complimentary add-ons are still offered by some sellers. We show that providing complimentary add-ons can be profitable for sellers with monopoly power under certain demand conditions. If these demand conditions are not met, it is optimal to charge a supplementary fee for the add-on. We also show how pricing policy can be designed to selectively target or deter different consumer segments from purchasing the add-on to boost sellers' profits, providing a strategic role for selling add-ons at either below-cost or at exorbitantly high prices. Yet such behavior may have repercussions for economic welfare when it results in socially inefficient giveaways when consumers would be better served with a lower price on the basic product without the add-on or, with the other extreme, when it results in excessively high prices for an add-on that restricts sales and leads to its underprovision from a societal perspective. The paper also provides managerial insights on the design and use of add-ons.