The U.S. Postal Service will impose its first-ever surcharge on packages to cover the rising cost of fuel, according to two people familiar with the matter.

The 8% surcharge will begin in April, and the current plan is to phase it out in January 2027, the people said. It will apply to packages but not letter mail.

A spokesman for the Postal Service didn’t immediately respond to a request for comment.

Other parcel carriers, including FedEx and United Parcel Service, have imposed fuel surcharges, as well as a basket of other surcharges and fees, for years. Both FedEx and UPS have dramatically raised their fuel surcharges in recent weeks as the price of oil has increased amid the turmoil in the Middle East.

Diesel prices reached $5.38 a gallon this week, up 51% from a year earlier.

The Postal Service has been struggling financially for years, and new Postmaster General David Steiner recently said that the agency will run out of money in a year. Last week, Steiner asked lawmakers to consider lifting regulatory restrictions on the Postal Service’s ability to raise prices.

The Postal Service’s losses stem in part from its mandate to deliver to more than 170 million addresses six days a week. The six-day-a-week statutory obligation leads to 71% of delivery routes being financially underwater, the agency has said. Roughly three in five post offices don’t cover the cost of their operations.

The post office has been trying to increase the volume of packages it delivers. It previously differentiated itself from commercial carriers by saying that it doesn’t apply residential, Saturday delivery or fuel or remote-delivery surcharges.