A proposed class-action lawsuit against Costco is seeking to secure refunds for customers who helped pay tariffs on imported products.

Seven Costco members — including four from Washington — sued the Issaquah-based big-box warehouse club chain Friday in the U.S. District Court of the Western District of Washington.

The lawsuit targets the company’s plan for handling President Donald Trump’s tariff refunds. Costco is one of several major retailers pushing for the Trump administration to refund them for duty payments.

Attorneys at Seattle law firm Emery Reddy and three other firms argue that Costco would make “windfall profits” by retaining the tariff refunds.

The lawyers and Costco didn’t immediately respond to requests for comment.

In March, Costco CEO Ron Vachris addressed the topic of tariff refunds in an earnings call.

“Our commitment will be to find the best way to return this value to our members through lower prices and better values,” he said. “We’ll be transparent in how we plan to do this if and when we receive any refunds.”

The proposed class-action suit would extend to people in the U.S. who bought Costco goods subject to tariffs under the International Emergency Economic Powers Act from Feb. 1, 2025, through Feb. 24.

The plaintiffs are seeking restitution of “tariff overcharges,” along with other forms of relief.

The Trump administration kicked off its trade war with various countries, including Mexico, Canada and China, in February 2025. It said the International Emergency Economic Powers Act gave it the ability to do so.

Faced with higher duties on imports, many American businesses — Costco among them — raised costs paid by customers in response.

Costco sued U.S. Customs and Border Protection in November, pushing the U.S. Court of International Trade to declare the tariffs as unlawful and to provide the company with refunds.

In February, the U.S. Supreme Court ruled against Trump’s ability to impose tariffs through the International Emergency Economic Powers Act. Chief Justice John Roberts delivered the opinion that taxing power lies in the hands of Congress, not the executive branch.

Now, businesses that shelled out for tariffs are entitled to refunds from the federal government, according to the Supreme Court decision.

Customs and Border Protection told the Court of International Trade last month that it’s developing a new arm of its system of record for imports that will calculate and provide refunds.

Once complete, importers and brokers will be able to submit claims through an online portal.

The federal agency expects to refund more than $130 billion, Bloomberg Law reported.

Attorneys suing Costco claim the company “stands to recover the same tariff payments twice” — and it hasn’t yet said it will return that money to customers.

Tariffs topped the agenda for Costco CEO Vachris in the quarterly earnings call on March 5.

“The future impact of tariffs remains extremely fluid,” he said. “It is not yet clear what the (refund) process will be, what refunds — if any — will be received and when this will happen.”

He asserted that the company didn’t pass the full costs of tariffs onto customers in many cases, and it’s difficult to track the full impact of changing tariff rates on individual items.

In its second quarter, Costco reported a year-over-year jump in total revenue to almost $70 billion from about $64 billion. Both net sales and membership fees improved compared to February 2025, rising to $68 billion from almost $63 billion for net sales and to $1.4 billion from $1.2 billion for membership fees.

Net income for the quarter was at about $2 billion, compared to close to $1.8 billion last year, per the earnings report.

Costco operates over 900 warehouses, including 634 in the U.S. and Puerto Rico. That includes about 30 stores in Washington.

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