Freight charges are the total dollar amount a shipper pays a carrier to move a load from point A to point B. But that total is rarely just one number. A typical freight invoice includes a base line-haul rate, a fuel surcharge, and a stack of accessorial charges that can quietly push the bill well past the quoted rate. For shippers in Kent, Washington and the Seattle-Tacoma corridor, understanding what each line item means is the difference between budgeting accurately and getting blindsided at month-end.
This guide breaks down the components of freight charges, explains the accessorials that catch shippers off guard, and shows how SeaSound Transport structures its drayage billing so clients in the South Sound area know the full cost before the truck leaves the terminal.
What Goes Into Freight Charges
A freight charge is built from two layers: the base rate and the accessorials. The base rate is what the carrier charges to move the freight a given distance with a given piece of equipment. Everything else layered on top is an accessorial.
The Base Rate
The base rate is the line-haul cost, typically quoted as a per-mile rate for truckload or a per-hundredweight rate for less-than-truckload (LTL). For drayage moves out of the Port of Tacoma or Port of Seattle, the base is usually a flat yard-to-warehouse rate for the first few miles, with a per-mile rate beyond that radius. Our freight cost per mile guide covers how that per-mile number is calculated and what drives it up or down.
Fuel Surcharge
Almost every freight invoice includes a fuel surcharge, usually calculated as a per-mile rate that adjusts weekly with the national average diesel price published by the Energy Information Administration. When diesel spikes, the surcharge rises in lockstep. It is not a markup, it is a pass-through, but it is the line item most likely to move between the day you get a quote and the day you receive the invoice.
Accessorial Charges: Where Surprise Costs Hide
Accessorial charges are fees for anything beyond a standard pickup and delivery. They are the line items most shippers do not see coming, and they are where a "quoted rate" and a "final invoice" diverge. Here are the accessorials that show up most often on drayage and truckload invoices in the Pacific Northwest:
- Detention. When a driver arrives at a warehouse and waits beyond the free time allowance, typically two hours, a detention fee accrues. At busy distribution centers in the Kent Valley, detention is one of the most common surprise charges.
- Chassis use. For intermodal drayage, the chassis the container rides on is rented separately. A daily chassis split fee applies if the container is not returned the same day. See our intermodal container guide for how chassis splits work at the Northwest Seaport Alliance terminals.
- Lumper fees. If the driver is required to load or unload the freight, a lumper fee applies. Some receivers mandate third-party lumpers, and the shipper pays regardless of who arranged it.
- Tolls and port fees. Terminal access fees, TWIC escort fees for restricted areas, and tolls on the SR 509 or I-5 corridor are passed through to the shipper.
- Storage and demurrage. If a container sits at the marine terminal beyond the free time window, demurrage accrues daily. Once the container is grounded at a yard, storage fees take over. For a full breakdown of how these costs stack, see our freight shipping cost guide.
- Reefer fuel. For refrigerated containers, the reefer runs on diesel and the fuel is billed separately from the truck's fuel surcharge.
How to Read a Freight Invoice
A well-structured freight invoice separates the base rate from each accessorial so you can see exactly what you are paying for. When reviewing a bill, check three things:
- Does the base rate match the quote? If the quoted rate was $4.50 per mile and the invoice shows $5.20, the difference is usually an accessorial that was not in the original quote, not a rate change.
- Are the accessorials itemized? A single "miscellaneous charges" line with no breakdown is a red flag. Every accessorial should have its own line with a description.
- Is the fuel surcharge current? The surcharge should reference a specific week's EIA diesel average. If it does not, ask the carrier how it was calculated.
For a broader overview of how freight billing fits into the full shipping process, our what is freight shipping guide walks through the lifecycle from booking to final delivery.
Avoiding Surprise Charges in the Seattle-Tacoma Corridor
Shippers in the Kent and South Sound area can reduce accessorial exposure with a few practical steps. Schedule pickup and delivery windows that give the warehouse enough time to load or unload within the free detention window. Confirm chassis availability at the terminal before the truck is dispatched, especially during peak import season when chassis pools run short. And always request a written rate confirmation that lists which accessorials are included and which are passed through at cost.
SeaSound Transport, based in Kent, provides drayage and truckload service out of the Port of Seattle and Port of Tacoma with upfront rate quotes that itemize the base rate, fuel surcharge, and anticipated accessorials. If you are shipping freight into or out of the Northwest Seaport Alliance terminals, request a quote and we will walk you through the full charge before the truck rolls.