Demurrage software counts one clock. The port runs another

Every product in this category shows you a date. The last free day, in a coloured chip, with a countdown beside it. It is the single most reproduced interface element in container logistics software, and on a large share of shipments it is answering a different question from the one the desk asked.

The date is the carrier’s. The container is also standing on somebody’s ground, and that party has a tariff of its own.

Two bills, two owners, one box

An import container that clears late can generate two separate charges for overlapping days. The carrier bills demurrage for the use of its container. The terminal bills a terminal storage charge for the use of its yard.

American rules put both under one definition, which is where a good deal of the confusion starts. 46 CFR § 541.3 defines demurrage or detention as charges assessed by carriers or terminal operators “related to the use of marine terminal space (e.g., land) or shipping containers, but not including freight charges”. One sentence, two objects: land, or box.

That definition is tidy in a US trade, where the carrier commonly bills both and the importer sees one line. Ship into Jebel Ali or Nhava Sheva and the tidiness disappears. The terminal has a published scale of rates, the carrier has your service contract, and the two documents do not agree about anything: not the number of free days, not the day the count starts, and not which days count.

Three days, or ten, from the same company

Take the two terminals, and read their own numbers.

Jebel Ali allows an ordinary import full container 10 free days, counted from the date of discharge from the vessel. After that it is AED 82 a day up to 20ft and AED 164 over 20ft for five days, then AED 153 and AED 306. The bands are in DP World’s published UAE Region tariff book and are set out in full on the Jebel Ali port page.

Nhava Sheva International Container Terminal allows 3. Section 9 of its scale of rates, in the edition indexed by 0.39% with effect from 1 May 2026, prices import FCL and LCL storage at nothing for days 0 to 3, then:

Both terminals are operated by DP World. JNPA’s own listing of its container terminals names the operator for NSICT, and the UAE tariff book is published by the same group. One company, two ports, and a free allowance that differs by more than a factor of three.

There is no regional rule to infer here, and no company policy to carry between lanes. The number belongs to the terminal.

The clocks do not count the same days

This is the part that decides disputes, and it is almost never written down outside the tariff itself.

NSICT’s note to Section 9 says the storage period “shall be reckoned from the day following the day of landing”, and that free dwell time “shall be exclusive of customs notified holidays and port non-working days”. Jebel Ali counts from the date of discharge. A carrier’s demurrage free time is ordinarily counted in plain calendar days from discharge.

Put those together on one shipment and you get two free periods that start on different days and burn days at different rates. A public holiday at Nhava Sheva costs a demurrage day and no storage day. Over a long weekend the two last free days can drift two or three days apart, in either direction depending on the port.

Three more clauses in the same section change the number materially, and none of them is visible in a countdown chip: hazardous containers are charged storage 25% above the ordinary slab, over-high and over-dimensional containers three times it, and dollar-denominated charges are recovered in rupees at the reference rate prevailing on the day the vessel entered port limits rather than the day of the invoice.

The test to run on a vendor

None of this is a reason not to buy software. It is a reason to ask one question before you do, and the answer sorts the category faster than a feature list.

Whose free time is the date on the screen?

There are three honest answers and one bad one.

1. The carrier’s, from a data feed. Most common. Fine, as long as you know it and hold the terminal’s tariff somewhere else.
2. The terminal’s, from its tariff. Rare, and useful mainly at ports that publish.
3. The earlier of the two, held per lane. What the desk needs.
4. We show the last free day. This is the bad answer, because it means nobody has asked the question, and the number on the screen is whichever one the integration happened to carry.

Ask it of any demurrage and detention software you are evaluating, including ours, and ask where the terminal side is stored. A product that cannot say is not wrong about the carrier’s date; it is silent about the second bill, which is the one that arrives after the argument about the first has been settled.

Why a second clock does not change the work

Holding two dates instead of one is a data problem and it is solved by typing. What neither date does is move itself.

The reason a container is still on the ground on day eleven is almost never that nobody knew the date. It is that a document pack was not finished: the bill of lading not released, the delivery order unsettled, the declaration queued behind an invoice a supplier has not sent. Packs routinely run about eight days late against free time, and a week of demurrage on a single container has cost US$12,000 — before the terminal’s storage bill is added to it.

Counting backwards from the earlier of two clocks is the arithmetic. Getting six parties to produce nine documents before that date is the job, and it is done by asking, and asking again, on the channels those people answer. That is the part how to choose demurrage and detention software comes down to, and it is why the date on the screen, whichever clock it came from, was never the product.