Understanding the difference between the two, and the practical ways to reduce them, is central to cost control in container imports.
Two different charges
Demurrage is charged while the container remains inside the terminal after free time expires; detention is charged for holding the container outside the terminal until it is returned to the line. They are calculated separately and can run at the same time.
Common causes
Late document preparation, delays in funding duty payments, missing permits, valuation or classification disputes, and slow arrangement of haulage for de-stuffing are the usual sources of these charges.
What actually helps
Preparing the customs file while the cargo is still in transit, checking free time before booking, securing permits early, and arranging inland transport before vessel arrival have by far the greatest effect.
