Steel coils sits in the yard at the Novolipetsk Steel PAO steel mill in Farrell, Pennsylvania, U.S., March 9, 2018. REUTERS/Aaron Josefczyk

WASHINGTON (Reuters) - The U.S. Commerce Department said it will begin accepting requests on Monday for product exclusions from President Donald Trump’s new steel and aluminum import tariffs, but it could take up to 90 days for the agency to make determinations.

In a notice published on Saturday on the Federal Register website, the Commerce Department said the effective date would be March 19 for its rules and procedures for the requests.

The agency said it anticipates that it will receive some 4,500 requests from U.S. businesses seeking exclusions for imported steel and aluminum products that are not available in sufficient quantity or quality from U.S. manufacturers.

But even if these are granted, companies could be forced to pay higher costs due to tariffs on their imported products for up to three months. U.S. Customs and Border Protection has been directed to begin collecting the 25 percent tariffs on steel and 10 percent tariffs on aluminum at 12:01 a.m. (0401 GMT) on March 23.

Reuters first reported on the Commerce Department rules and procedures from a draft document seen on Friday. The published notice matches the draft, with the effective date filled in.

The final notice can be seen: here