Fuel surcharge
An adjustment added to the freight rate to pass fuel price changes through to the customer.
A fuel surcharge is an amount added to a freight rate to reflect the price of diesel, so that the carrier's base rate is not eaten by fuel swings. It is usually calculated from a published fuel price index, with a formula stated in the contract or rate confirmation that sets a base price and an adjustment per mile or per percentage above it.
The details matter for cash: which index, which week's price, whether the surcharge is paid on all miles or loaded miles only, and whether it is included in an all-in rate. Some contracts fix the surcharge for a period; others move weekly. Where a quick-pay discount applies, it is commonly taken on the surcharge as well.
General information, not legal or financial advice.