Demurrage vs. detention: what's the difference and why it matters for a dispute

These two terms are used together so often that many treat them as synonyms, or as one combined concept. In reality, they describe two different stages of a container's life, with different contract terms, sometimes even different rates. And when it's time to dispute an invoice, this exact difference often determines whether the claim is correct at all.

Demurrage — while the container is at the terminal

Demurrage applies to the period when a container sits at the terminal (port or rail yard) after discharge, but hasn't yet been picked up by the consignee. If the contractual free time — say, 5 days — runs out while the container is still at the terminal, the carrier starts charging demurrage for every additional day until the container leaves.

Detention — while the container is with the consignee

Detention applies to a different period — from when the container left the terminal (picked up by the consignee) until the empty container is returned to the carrier. That's an entirely different time window, often with its own, separate contractual free time, which can differ from the demurrage free time even within the same contract.

Why this difference actually matters

In practice, confusion arises for several reasons. First, some invoices use both terms interchangeably, or merge them into one combined line, without specifying which period belongs to which charge. Second, contracts often set different free-time terms for demurrage and detention — say, 5 days for demurrage but only 3 for detention — and if an invoice calculates both amounts using the same free time, that's already a concrete, checkable discrepancy.

Third, and most important for a dispute: the moment the container left the terminal (the gate-out date) is the boundary between the demurrage and detention periods. If that date is stated incorrectly on the invoice, or not stated at all, it's impossible to verify whether the charge was assigned to the correct period — which means it's impossible to verify whether the correct rate and the correct free time were applied.

What this means in practice

Before disputing an invoice, the first step is determining whether a given line is demurrage or detention, and comparing it against the corresponding free time and rate in the contract — not a generic one. If an invoice doesn't make this distinction clear, that in itself is grounds to ask for a breakdown before paying — a fairly calculated invoice can always show which amount belongs to which period.