A detention invoice lands in your inbox for a container you picked up on time, or so you thought. The line-haul carrier says the clock started when the container hit the terminal. You say it started when your appointment was confirmed. Nobody agrees on the math, and the invoice sits there getting more overdue by the day. Detention billing errors happen constantly at Port Miami, and most shippers pay them without checking the numbers.
How the Detention Clock Actually Works
Detention and demurrage get mixed up constantly, and the confusion is the root of most billing fights. Demurrage is a port-side charge — the steamship line bills you for a container sitting at the terminal past free time. Detention is different. It's charged when the drayage carrier's equipment, the chassis and container, sits outside the terminal past an agreed free period, usually at your warehouse or yard.
Rates after free time run $50-100 per hour in South Florida, sometimes billed in daily blocks instead. A contract that's vague about which method applies is a contract that gets disputed later. Read yours before your next shipment, not after the invoice arrives.
Common Billing Errors That Inflate Your Invoice
We've reviewed hundreds of detention invoices from other carriers over the years. The same handful of errors show up again and again.
- Clock started at port gate-out, not warehouse arrival. If your facility is 25 minutes from the terminal, that's 25 minutes of billed detention you never actually incurred.
- No check-in timestamp recorded. Without a gate log, ELD ping, or driver check-in call, the carrier is estimating your arrival time — usually in their favor.
- Lunch or driver break time included. A driver who takes a 30-minute break while waiting isn't detained by your facility; that's the driver's own downtime and shouldn't hit your invoice.
- Double-billed on split deliveries. If one container serves two stops, some carriers charge full detention at each stop instead of splitting the free time across both.
- Wrong rate applied. Contract says $65/hour, invoice shows $85/hour. This happens more often on invoices generated by outdated rate tables in the carrier's TMS.
- Detention billed for a delay the carrier caused. If the truck showed up late to begin with, or the driver got lost, that time isn't yours to pay.
None of these are necessarily malicious. Most trucking companies run detention billing off manual timestamps entered by dispatch, and manual entry means manual mistakes. The problem is that mistakes rarely get caught unless the customer checks.
What to Request Before You Dispute
Don't dispute based on gut feeling. Pull the paper trail first.
If the carrier can't produce a gate timestamp or GPS ping for a disputed charge, that's a strong argument on its own — an unverifiable charge is an unenforceable charge.
Building a Dispute That Gets a Credit
A vague email saying "this seems wrong" gets ignored. A dispute with line-item math gets a credit. Structure it like this:
- Reference the invoice number and the specific line item you're disputing.
- State the contracted free time and rate, quoting the section of your rate agreement.
- Show your calculation of what the charge should be, with your supporting timestamps attached.
- Show the carrier's calculation and where it diverges from yours.
- Request a corrected invoice or credit memo within a set number of business days — 10 is standard.
- Attach every document: gate records, GPS data, signed BOL, sign-in log.
Carriers respond faster to disputes that arrive with evidence than disputes that arrive with frustration. The math should do the arguing, not the tone of the email.
Who to Send the Dispute To
Send disputes to the billing department in writing, not the dispatcher who booked the load. Dispatchers usually can't touch invoices, and a verbal complaint to them doesn't create a record. Copy your account rep so there's a person accountable for follow-up, and keep every dispute in a dedicated email thread rather than mixed into daily booking correspondence.
If a carrier won't correct a clearly documented error, escalate to a manager and set a firm deadline before you involve a third party. Small claims court is rarely worth it for a few hundred dollars, but a pattern of unresolved disputes is a reason to switch carriers.
Preventing Future Detention Disputes
The best dispute is the one you never have to file. A few habits cut down on billing errors before they happen.
- Get a written detention policy in your rate agreement — free time hours, billing increments, and what counts as the start/stop trigger — before your first load, not after your first dispute.
- Track your own arrival and departure times at the dock. A simple sign-in sheet with time stamps is enough.
- Ask carriers upfront whether they track detention with GPS or manual entry. GPS-tracked carriers produce fewer disputed invoices.
- Review invoices within a few days of receipt, while gate records and GPS data are still easy to pull. Some terminal systems purge logs after 30-60 days.
- Batch your detention questions into a monthly review instead of fighting every invoice one at a time. It's easier for both sides to reconcile a month of charges together.
At One A Trucks, every load runs on GPS-tracked arrival and departure times tied directly to the dispatch system, and detention charges reference those timestamps automatically. If a customer questions an invoice, we pull the raw data the same day. That transparency is what keeps a billing disagreement from turning into a dispute that drags on for weeks.