Will Chyrsanthos wanted something striking for his entryway bathroom. So last year, while doing home renovations, he imported a sky-blue concrete sink from Bulgaria. The ramp sink ended up costing him an extra $250 because of tariffs.

When U.S Customs launched its online portal Monday to start the process of refunding $166 billion in tariff revenue, Chyrsanthos logged in to get the money back.

But he soon found out the portal wasn't for most individual customers. Instead, the refunds would go to whoever directly paid Customs as the importer of record, often a U.S. company. For Chyrsanthos and millions of other American consumers, if they want a tariff refund, they will have to rely on the goodwill of companies to pass those refunds along, or on class action lawsuits to force a return.

Chyrsanthos was pessimistic — but then he got a bit of news. The shipping company DHL, which he'd used to import his expensive sink, announced it would provide refunds for customers who had paid tariff fees to them directly.

"Now that's unexpected and wonderful," Chyrsanthos says.

FedEx and UPS also promised similar refunds for customers. For these shipping companies, it's an option because there is a clear paper trail of how much each client paid — and now is owed.

But what about all of the other products Chyrsanthos bought for his Massachusetts home renovation? He has no such paper trail. The extra cost was baked into the final price of each item he bought, rather than listed as a separate fee on a shipping bill. He suspects the total price increase was in the thousands.

"I have zero hope for recouping any of that," Chyrsanthos says.

Retail companies are facing the same problem: They don't know how much of a tariff burden they passed on to each customer. And that is perhaps the biggest barrier stopping retailers from sharing whatever refunds they are able to claim from the government.

"It's nearly impossible to determine how much individual consumers paid," says Terence Lau, dean of Syracuse University College of Law.

That's because a product, like a TV, often has parts from multiple countries, and each was hit with different tariff rates. Those rates changed over time by presidential decree, which makes calculating a customer's actual cost even more difficult. Plus, the retailer likely absorbed some of that tariff expense. The tariff burden was also shared up and down the supply chain, between vendors, distributors and finally customers.

"By time it gets down to the consumers, the whole tariff has been diluted," says Robert Shapiro, an international trade lawyer and partner at the law firm Thompson Coburn.

Rebecca Melsky co-founded Princess Awesome, a clothing company that sells clothes for girls that include traditionally boy-coded images, like dresses with solar systems on them or lounge pants with pictures of dragons. She says she has no way to automatically determine how much each customer paid in tariffs, and calculating it individually for each transaction would be "incredibly laborious."

Plus, Melsky says her company has already spent significant time dealing with tariffs. "That doesn't count in dollars, but time is worth money," Melsky says.

To cope with tariffs, she raised prices and put up an online tariff tip jar for donations. Today, as a kind of refund, she is considering giving $10 in store credit to customers who contributed to the jar.

Other retailers are also looking for other ways to pass recouped money along to customers without dealing with the headache of full refunds. Costco's CFO Gary Millerchip said on a recent earnings call that the company could pass along the returned tariff dollars as lower prices.

Several class action lawsuits have been filed against large companies, arguing that since they shared the tariff cost with consumers, they should also share the tariff relief.

Edwin Martinez, an engineer, paid specific tariff charges for online purchases of electronic components, like power connectors and pressure sensors. Now he's a little annoyed, knowing he likely won't get a refund.

"I paid this extra tax, man," Martinez says. "Can I just have my money back?"