U.S. companies seeking to avoid paying tariffs on steel and aluminum may have to wait as long as 90 days before an exclusion is granted.

On Sunday March 18 the U.S. Department of Commerce released the procedures that U.S. companies must follow to exempt specific products from the Trump administration’s impending tariffs on steel and aluminum, “a move that came as companies and governments continued to lobby feverishly to scale back the duties,” Law 360 reports.

The review period for such requests “normally will not exceed 90 days, including adjudication of objections submitted on exclusion requests,” Commerce said in a statement.

The U.S. Customs and Border Patrol is scheduled to begin collecting the tariffs of 25% on steel and 10% on aluminum at 12:01 a.m. on March 23, meaning fastener manufacturers who import wire rod and other steel products could end up paying the tariff for months until an exclusion is granted.

“An exclusion will only be granted if an article is not produced in the United States in a sufficient and reasonably available amount, is not produced in the United States in a satisfactory quality, or for a specific national security consideration,” the Commerce Department stated.

“Separate exclusion requests must be submitted for each unique steel or aluminum product import. For an exclusion request to be considered, the requester must provide a full factual description of the specific product, its properties, and its quantity.”

Commerce estimates about 4,500 individual requests would be filed for exclusions from steel and aluminum tariffs and about 1,500 of these would draw objections from interested parties, according to CNBC.

Exclusion requests will be posted for a 30-day comment period on regulations.gov.