DEM, DET, storage and free time: verify the charging basis

Overview

Common usage associates demurrage with terminal container time, detention with equipment outside, and storage with port/depot space. Carriers and markets may use separate or combined arrangements, so actual tariff definitions govern.

Free time needs a start and an end

GENLOG recommends recording the triggering events, calendar or working-day basis and equipment type, not just “five free days”. Carrier free time should not be assumed to waive every terminal storage charge.

Separate each charge and its clock

A DEM, DET or storage label is not enough to calculate an invoice. Obtain the tariff for provider, location, equipment, import/export movement and applicable period. Combined D&D arrangements also exist; one formula cannot serve every shipment.

Audit an invoice in six steps

1. Obtain the booking, confirmed free-time agreement and applicable tariff. Distinguish an indicative quote from shipment-specific confirmation.
2. Collect actual events required by that tariff, such as discharge, availability, collection and empty return.
3. Establish calendar or working days, first/last-day inclusion and holidays. Do not automatically exclude Sundays.
4. Build a daily ledger, mark free days and allocate paid days to tariff tiers. Check equipment count, currency, tax and separate facility items.
5. Reconcile each invoice line with events and evidence. Preserve rejected empty-return appointments and missing records for review.
6. Request clarification or dispute through the designated channel within its deadline. A dispute does not automatically suspend every charge.

An explicitly hypothetical tariff

Assume one agreed clock allows six free days with first and last-day treatment already defined. Event reconciliation leaves five chargeable days. A hypothetical tariff charges 50 USD for each of the first two paid days and 75 USD for each of the next three: 2 × 50 + 3 × 75 = 325 USD for one container before other charges or tax.

This does not imply that a particular carrier always grants six days or starts counting at discharge. For multiple containers, reconcile each event history before multiplying. Facility storage may have a distinct scope; check whether it runs concurrently, is included or requires an overlap explanation.

Common questions

• Does free time waive all port charges? Identify which clock the allowance covers.
• Are closed-depot weekends automatically free? Check applicable terms and obtain a decision supported by evidence.
• What if no empty-return location accepts the box? Request written instructions, retain appointment/rejection evidence and notify the provider promptly.
• How can exposure be reduced? Track each container’s last free day, plan clearance and trucks early, and confirm depot hours before dispatch.

Keep the event evidence

Retain free-time confirmation, applicable tariff, discharge, gate-out and empty-return records. Reconcile events as well as rates. For disputes, follow the billing party’s process with evidence rather than requesting an estimated day deduction.

References

GENLOG practical guide, reviewed on 24 October 2026 using public primary sources. Examples are illustrations, not official tariffs or contract templates.

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