Quick answer: A fixed discount is a set percentage off a shipping service that does not change during your contract. An earned discount is a volume-based discount that depends on how much you spend with the carrier, so it can rise or fall from week to week. Most contracts use both, and your real price depends on how they combine. If you ship with UPS or FedEx on a negotiated contract, your carrier discounts almost always come in two forms: fixed discounts and earned discounts