Costco found a use for its tariff windfall that deserves investors’ attention: give some of it back to shoppers. In its September 24 earnings release, the warehouse retailer reported higher profits while disclosing that part of its tariff refunds had been reinvested in member value.
For quality investors, that choice poses a useful challenge. A competitive advantage is often described as the ability to charge more. Sometimes the more durable advantage comes from being able to charge less—and having the discipline to keep doing it.
The growth is real. The windfall is not recurring.
For the 16 weeks ended August 30, net sales rose 11.2% to $93.9 billion. Comparable sales, excluding gasoline-price and currency movements, increased 6.7%. Diluted earnings reached $6.75 a share, versus $5.87 a year earlier, including a non-recurring $0.15 benefit from tariff refunds after partial reinvestment in member value.
The distinction matters. Stripping out a disclosed windfall is not an exercise in pessimism; it is the starting point for deciding what shareholders can reasonably expect to recur. A refund can improve a quarter without improving the underlying economics of selling the next pallet of groceries.
Likewise, adjusted comparable sales are more informative than a headline revenue jump when fuel prices and exchange rates are moving. But even that measure does not establish how much growth came from higher prices, greater shopping frequency or larger baskets. Investors should resist making the statistic answer a question it was not designed to answer.
The customer receives part of the moat
Costco’s 2025 annual report describes a tightly linked operating system: a limited assortment, large purchasing volumes, efficient distribution and rapid stock turnover. It says merchandise is often sold before payment to suppliers is due. These are practical advantages, not simply expressions of brand affection.
The economic logic runs in a loop. Concentrating demand on fewer products can strengthen purchasing terms. Lower prices can attract more business. More throughput can spread operating costs across a larger sales base. Passing some savings to customers can therefore be an investment in future competitiveness rather than evidence that management has failed to maximize profitability.
My reading is that the tariff-refund decision belongs in that category. It does not prove every price investment will earn an attractive return. It does show why judging a retailer solely by how much margin it extracts today can miss the asset it is trying to preserve: the customer’s confidence that renewing the membership remains worthwhile.
That confidence is valuable precisely because shoppers retain alternatives. Membership is not an irrevocable contract, and reputation is not a patent. A retailer that gradually makes its offer less compelling may report stronger margins for a while, even as it weakens the reason customers came in the first place.
Recurring revenue still has to be earned
Quarterly membership fees reached $1.85 billion, up from $1.724 billion. These fees are revenue, not a separate pool of pure profit. Warehouses, staff, technology and attractive merchandise are all part of delivering the proposition members pay for.
Costco’s membership structure illustrates the bargain. U.S. Gold Star membership costs $65 annually; Executive members receive a 2% reward on qualifying purchases, subject to a cap. The fee buys access to an ongoing commercial relationship, while rewards give higher-spending households another reason to concentrate purchases.
The analytical task is to test whether that relationship is deepening. Renewal rates, membership additions and spending behavior deserve to be read together. Fee growth alone can reflect pricing or membership mix as well as a larger customer base. None should be mistaken automatically for an equivalent improvement in loyalty.
There is also a useful warning for investors hunting for the next Costco. A subscription label does not create a moat. Customers must continue receiving something difficult to reproduce at comparable value. Otherwise recurring revenue is merely revenue waiting for a cancellation.
A strong business is not a blank check
For fiscal 2026, operating cash flow was $15.825 billion and property-and-equipment spending was $6.435 billion. Subtracting the latter leaves roughly $9.39 billion, before other investing and financing flows.
That cash generation is encouraging, but a valuation still needs assumptions about future reinvestment, growth and the return investors require. Excellent execution cannot rescue every purchase price. Paying today for decades of uninterrupted success leaves little room for ordinary setbacks, let alone a change in competitive conditions.
The most useful lesson from these results is therefore behavioral rather than numerical. Look for management teams willing to protect the customer proposition when they could instead flatter a quarter. Then apply the same discipline to the stock: admire the business, normalize the earnings and insist that the price leaves something for the investor.
