Accessorial shipping charges stem from extra services performed by the carrier that goes beyond the typical dock to dock. Common examples of these charges are lift gate service, residential pickup or delivery, limited access locations and inside delivery.
If you don’t have all the specifics of your freight as it relates to potential accessorial charges, you could be in for a big shock when your freight bill arrives, as accessorials can cause an unanticipated  25-40% increase in your freight charge. Fortunately, the unnecessary costs (or at least the surprise) are avoidable. Understanding accessorial charges up front will help you to better control freight costs.

Limited Access (Pick-up or Delivery)

Schools and churches
Fairs/Carnivals-Site where the consignee does not have a permanent location.
Mines- Includes all facilities at mine site (warehouses, offices, etc). Normally these are in remote locations.
Mini-storage facilities
Constructions sites- Must be a true job site. A customer with “construction in their name does not necessarily mean construction site.
Military Installations- When required to enter a US military installation.
Prison- When required to enter a secured area.
Non-standard equipment- Can only be accessed withy a straight truck.
Limited Access doesn ‘t include constraints that prevent the vehicle from getting closer than 65 feet to the shipper/consignee for loading and unloading. This is considered Inside Delivery/Pick up.

Inside Delivery or Pick-up (Also includes long carry)

Driver has to take the freight far enough away from their unit that they must close and secure the trailer.
Driver must pick up or deliver freight into a building through a second door or to a different floor.
The total distance from the rear of the trailer to the customer ‘s dock/door is more than 65 feet from the trailer and outside the building.

Liftgate (Pick-up or Delivery)

Driver is requested to use a liftgate by the customer at pick-up or delivery or it must be used to complete the pick-up or delivery (no other way to unload or load the product).

Residential (Pick-up or Delivery)

Delivery or pick-up at a home that is not open to the public during normal business hours.
Residential delivery includes Inside Delivery.

Sort and Segregate (Delivery only)

Driver is required to remove freight from one pallet to restack another pallet.

Marking and Tagging (Pick-up only)

Driver is required to alter the markings or tags on any pieces of freight.

Thee are the the most common accessorial charges. Ask your freight company for a list of their accessorial charges to make sure you understand what you could be getting into before shipping.  Some accessorial charges can be negotiated to a flat rate or even waived altogether. But your best defense is to understand all the possible charges ahead of time.
Photo Credit: Xnatedawgx (Own work) [CC BY-SA 4.0], via Wikimedia Commons. Click on image to view source.