How to dispute a demurrage or detention invoice (step by step)
The exact process for disputing a container demurrage or detention invoice with any carrier: evidence to pull, the eight billing errors to check, dispute-window discipline, and template language.
The five steps
Pull the evidence before you argue: the invoice, your carrier contract (or the quoted tariff), the bill of lading, and the terminal's own event data — discharge date, gate-out date, empty-return date. The dispute is won or lost on these four documents.
Check the clock, not the charge. Most successful disputes aren't about whether a delay happened — they're about mechanics: demurrage billed from vessel arrival instead of container discharge, detention billed from discharge instead of gate-out, negotiated free time not applied, the wrong tariff tier, weekends or port closures counted against you, or demurrage and detention overlapping the same days.
File inside the window. Invoice terms typically give a short dispute window — often 21–30 days from invoice date — and claims raised after it are routinely refused regardless of merit. Diarise it the day the invoice lands.
Dispute through the carrier's own channel (portal or disputes inbox) in procedural language: cite the invoice number, the contract clause, and the terminal timestamps, and state the corrected calculation. Attach everything. Angry emails lose; documented recalculations win.
Chase to a credit note. A dispute that is 'acknowledged' is not money. Track every case to an issued credit note or corrected invoice, and record the outcome — what worked against this carrier at this port will work again.
The eight errors that pay for the effort
1) Wrong clock start — demurrage from vessel arrival instead of container discharge. 2) Wrong detention start — from discharge instead of gate-out. 3) Negotiated free time not applied. 4) Wrong tariff tier or port tariff. 5) Weekends, holidays and closures counted when your terms exclude them. 6) Days you couldn't collect the box — carrier hold, terminal appointment shortage. 7) Demurrage and detention overlapping the same days. 8) Non-compliant or late invoices — on US trades OSRA requires thirteen specific invoice fields, and contracts usually set an invoicing window; failures can void the charge entirely.
Template language that works
"Re invoice [number]: the invoice charges [X] days of demurrage calculated from [date]. Per clause [Y] of our service contract, free time is [N] days commencing at container discharge, which terminal records show occurred on [date]. The correct charge is [Z]. Please reissue the invoice or credit the difference. Supporting documents attached: contract extract, terminal event report, original invoice." Procedural, cited, attached — that is the whole art.
The economics of checking
Checking one invoice properly takes an experienced person half an hour to an hour, which is why most invoices are paid unchecked. That is the entire reason Marevo exists: the AI reads the invoice against your contract and the terminal data in seconds, drafts the dispute, and only earns when money actually comes back. The retro-audit of your last 90 days of invoices is free.
Frequently asked
What's the success rate of demurrage disputes?
Roughly 20–30% of charges are overturned when disputed with documentary evidence — and higher on portfolios that have never been audited, because systematic errors (like unapplied contract free time) repeat across every invoice.
Will disputing damage my relationship with the carrier?
No. Carriers run dispute desks precisely for this; a documented recalculation through the official channel is routine commerce. Paying wrong invoices silently is not a relationship strategy — it's a subsidy.
Find out what your last quarter owes you
Marevo reads your invoices against your contracts and the terminal data, drafts the disputes, and is paid mostly from what actually comes back. The audit itself is free.
Claim the free audit