additional fee; extra charge; surcharge
A fee added on top of a base price, commonly used in travel, shipping, and service contexts.
At this hotel, breakfast is available at no extra charge.
If your baggage exceeds the weight limit, an additional fee will be charged.
An extra charge applies for large suitcases.
I paid an extra fee to change my seat.
With this plan, you can check up to two bags with no extra charge.
An extra charge is incurred for late-night delivery.