There is an episode of The Office where Michael gives a business five "10% off" coupons and forgets to write "Coupons cannot be combined." In the episode, the business claims they can use the coupons for 50% off.

But that got me thinking, even if you forgot to write "Coupons cannot be combined," is there an argument that the coupons would have to be used sequentially rather than stacking them? In other words, instead of saying the discount is 10+10+10+10+10=50%, could you argue that the end price should actually be 90% X 90% X 90% X 90% X 90% = 59%, for a discount of 41%?

Can you "stack" coupons as in the episode, or do they have to be applied one at a time?

3 Answers 3


"10% off" would be taken to mean "... from the original price" unless otherwise specified, even to someone well aware of geometric growth.

Given that there are a number of loyalty saver schemes that stack percentage discounts additively, and that schemes disallowing stacked discounts make this clear, a reasonable person would expect that in the absence of such specification, they can stack the discounts as described in the question.

  • "This answers seems self contradictory - if it means 10% off the original price there is no stacking since there is only one original price. Mar 6, 2020 at 20:39
  • Yes, there is only one original price, and taking 10% off that original price ten times would remove all of it.
    – user4657
    Mar 6, 2020 at 20:42
  • The way I see it, any procedure (doing it "ten times", as you say) would be sequential and after the first 10% is taken off, the result is no longer the original price so the second set is meaningless. Mar 6, 2020 at 20:52
  • 1
    A discount is a reduction applied to the original price based on that price, whether done as 30 individual percents or a single thirty-percent chop, the result is the same, and that is what any reasonable person would expect.
    – user4657
    Mar 6, 2020 at 20:55
  • 1
    A discount doesn't change the original price, it reduces the amount that will be actually paid. Reducing the expected payment by multiple separate amounts is possible even when they are all decided based on the original price. Perhaps you are too used to coupons that disallow combination with other offers and have assumed that this is a requirement of any discount, either mathematically or logically - it isn't.
    – user4657
    Mar 6, 2020 at 21:37

Would Multiple Coupons Stack or Apply Sequentially? Can you "stack" coupons as in the episode, or do they have to be applied one at a time?

It all depends on the terms and conditions of the [provider's] offer. Absent a contractual language that addresses the issue unequivocally, the controversy would depend on the competing criteria of doctrine of contra proferentem and usage of trade. The former favors the customer, whereas the latter favors the provider.

The lack of disclaimers such as "Coupons cannot be combined" triggers the doctrine of contra proferentem, whereby the customer is entitled to combine/use multiple coupons in a way that is most lucrative to him.

To overcome the doctrine of contra proferentem, the provider would need to prove that its position constitutes "usage [of trade] having such regularity of observance [...] as to justify an expectation that it will be observed with respect to a particular agreement", such usage "establishing a common basis of understanding for interpreting their expressions and other conduct". See Restatement (Second) of Contracts at § 222-223.


It depends on the coupon

Let's look at a coupon I happen to find... It reads:

10% Off*

What is the asterisk for? It shows that terms and conditions apply. They are written tiny at the bottom of the coupon.

*the listed price in the manufacturer catalog. 1 Coupon per purchase.

This coupon can't be stacked, and even with 10 and 10 items, you can only apply one coupon per purchase, so you need to do 10 separate purchases. Let's modify the clause a little.

*the listed price in the manufacturer catalog. 1 Coupon per item.

You still can't stack them. You get one item free if you have 10 coupons and buy 10 items. How about this version?

*the listed price in the manufacturer catalog.

Now it becomes ambiguous... but the base price is defined as in the manufacturer catalog. So if the store has a reduced or raised price, the discount is still calculated from that price. Let's say the listed price is 100$, then even in a store where the item costs 200$, you only get 10$ off, and it is up to store policy if you can apply multiple coupons. But if it is in store for 50$, you still get 10$ off.

*the listed price in store.

Now the listing price doesn't matter, but you calculate the price in-store from the listed store price. That's the price on the shelf. And it's up to store policy how many they accept per purchase and item.

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