UPS and FedEx have begun filing for some tariff refunds

The refund process for tariffs has begun, but it could be months before consumers start reaping those rewards.

Following the Supreme Court ruling that some tariffs were unconstitutional, U.S. Customs and Border Protection opened up a refund process on Monday for companies to begin requesting money back.

The refund process only affects levies collected under the International Emergency Economic Powers Act, or IEEPA, which were the specific tariffs that the Supreme Court invalidated. Some tariffs —like those under Section 232 of the Trade Expansion Act of 1962 or those under Section 301 — remain in place.

The tariff refund portal, called the Consolidated Administration and Processing of Entries, will allow importers of record to submit refund requests. CBP will then process those requests in phases, and the first phase will only cover refund requests for entries that CBP finalized within the last 80 days.

For shippers UPS and FedEx, that could mean a payday for the companies and, eventually, for customers.

UPS said this week that it will work to request and retrieve tariff refunds from CBP on customers' behalf for any shipments where the company was the importer of record, meaning customers do not need to contact UPS.

Still, the company noted that the refunds could take up to three months to be delivered to UPS, which can only then issue refunds to customers.

"We remain focused on keeping shipments moving and helping ensure our customers can fully exercise their rights throughout this complex process," UPS said in a statement. "We are closely monitoring legal developments and will share updates as available."

The shipment company said it has only received CBP guidance about the first phase of tariff refunds.

FedEx also told CNBC it has begun filing claims with CBP for tariff refunds.

"Supporting our customers as they navigate regulatory changes remains our top priority," FedEx said in a statement.

The company said its process is "straightforward": If CBP issues refunds to FedEx, it will in turn issue those refunds to shippers and consumers who paid those charges.

FedEx said it will also generate the reports needed to secure refunds on behalf of its customers.

DHL told CNBC it has also begun filing for tariff refunds, launching the process automatically for any shipments where it was the importer of record.

"We will continue to monitor developments closely, engage with authorities and communicate transparently as further guidance becomes available," the company said in a statement.

On Tuesday, President Donald Trump told CNBC's "Squawk Box" that he would "remember" companies that did not request tariff refunds.