The Discount That Stacked Three Deep

A customer qualified for a referral discount (5%), then a loyalty discount for being on the books over three years (5%), then a volume discount for a bigger order that quarter (8%). Each one, on its own, was approved by someone at some point for a good reason.

Nobody had ever built a rule for what happens when a customer qualifies for more than one at the same time. So they all applied, automatically, stacking to an 18% discount on an order that was supposed to be a strong-margin quarter — and nobody caught it until the controller noticed that account's margin had quietly gone negative.

Three good decisions, made separately, by three different people, added up to one bad one nobody actually made.

Do any of your discount types stack automatically — and if a customer qualified for three of them at once, would anyone catch it before the invoice went out?