Per Diem Charge 

A per diem charge, also referred to as detention, is a fee applied by a carrier or container leasing company when a shipping container is returned late. 

Per diem means “by the day” in Latin, and a per diem charge is a late return fee that accumulates for each day a container is not returned to port past the agreed free time. When leasing a shipping container from a leasing company or carrier, it is important to know how many days of free time are covered in the contract. A shipper can then be certain of how many days they can use the container without incurring additional late fees. 

Why Are Per Diem Charges Important? 

From the point of view of a carrier, container lessor, and the wider supply chain, having empty containers returned to port on time helps sustain the flow of cargo. If significant quantities of containers build up inland on a large scale, then this backlog can cause equipment shortages elsewhere in the supply chain. 

Because carriers want to keep as many containers in circulation as possible, per diem charges are used to incentivize prompt returns.