Chassis rental and container per diem

Also invoiced as: chassis usage charge · chassis split fee · container per diem · equipment per diem · daily use charge · DUC

What these charges are

Chassis rental and container per diem are two separate rentals billed on the same inland move. Chassis is the wheeled frame the container rides on: you pay a daily rate to whoever owns it — a pool operator, the motor carrier, or the ocean carrier under a merchant-haulage tariff. Per diem is the rental on the container box itself once the ocean carrier’s free time expires. They run on different clocks, are owned by different parties, and are routinely billed for the same days without either party checking the other.

How they are calculated

Chassis daily rate	A flat per-day rate set by the pool or motor carrier, typically billed from the day the chassis leaves the pool to the day it is returned, including weekends unless the tariff says otherwise.
Chassis split fee	A one-off charge when the container and the chassis are picked up at different locations. Legitimate only when the split was actually performed.
Per diem free days	The ocean carrier’s contractual free time on the container, counted from gate-out at the terminal. Contract free time overrides the published tariff.
Per diem daily rate	A tiered daily rate on the box after free time, escalating in bands (for example days 1–5, 6–10, then 11+), reefers and specials at a higher tier.
Stop-clock events	Days that must be excluded: terminal appointment unavailability, terminal or rail closure, chassis shortage, and any period the empty was tendered for return but refused.

Worked example — one dry 40ft, Chicago inland delivery

Gate-out 04 Mar, empty returned 14 Mar = 10 calendar days on the chassis.
Chassis at $32/day x 10 = $320.
Contract per diem free time: 5 days. Days 1-5 free.
Per diem days 6-10 = 5 days at $115/day = $575.
Return refused 12 and 13 Mar (no empty appointment) = 2 days excluded.
Corrected per diem: 3 days x $115 = $345. Variance recovered: $230.

The refusal days are the recoverable part. Proof is the appointment-system screenshot or the trucker’s refused-return record for those two dates — not a phone call.

The 4 ways these lines get overbilled

Per diem charged on days the empty could not be returned

The clock is supposed to stop when the return is blocked by the terminal or the railroad: no empty appointment available, gate closed, stack full, or the carrier refusing that box type. In practice the billing system counts calendar days from gate-out to gate-in and knows nothing about refusals, so every blocked day is invoiced.

How to prove it
Appointment-portal screenshots showing no available slot for the return date, the terminal’s published closure or stack-full notice, and the driver’s refused-return record with a timestamp.

Chassis and per diem billed for the same days by two parties

When the ocean carrier supplies both the box and the chassis under merchant haulage, and the motor carrier also bills a chassis day from its own pool account, the same physical day is paid twice. The two invoices arrive from different vendors weeks apart, so nobody reconciles them.

How to prove it
Both invoices side by side against the single interchange record (EIR) for that container, showing one chassis in use on the overlapping dates.

Tariff free time applied over the contracted free time

Service contracts frequently negotiate extended inland free time — 7 or 10 days instead of the tariff’s 4 or 5 — but the billing engine prices off the tariff in force at invoicing. Every day of the negotiated extension gets billed at the first-tier per diem rate.

How to prove it
The signed contract clause with the free-time figure and its effective dates, matched to the bill of lading date, not the invoice date.

Split and re-pull fees for moves that never happened

Chassis split, pre-pull, dry-run and yard-storage lines are billed as standard add-ons on lanes where they are common, whether or not the individual move required them. A pre-pull billed on a same-day live unload is the clearest example.

How to prove it
The driver’s trip record and gate timestamps for that container showing a single continuous move, against the accessorial line claiming a second pull.

Common questions

What are accessorial charges?

Accessorial charges are the line items on a freight invoice that sit outside the base linehaul rate — chassis rental, per diem, detention, storage, pre-pull, split, layover, fuel and similar. On US inland moves they routinely exceed the linehaul itself.

What is the difference between chassis and per diem?

Chassis is rental on the wheeled frame, billed by the pool or motor carrier. Per diem is rental on the container box, billed by the ocean carrier after its free time expires. Two owners, two clocks, two invoices — often for the same days.

Is per diem the same as detention?

They overlap in practice but not in origin. Per diem is equipment rental on the box. Detention is the charge for holding the driver and the chassis beyond the free window at a facility. Some carriers merge them into a single combined line, which is where double recovery starts.

Can per diem be disputed after the invoice is paid?

Usually yes, but the window is short — many tariffs set a dispute period measured in months from the invoice date, so paid invoices are triaged oldest-first before the window closes.

What proof do carriers accept for a blocked return?

Documentary evidence tied to a date: appointment-system screenshots, terminal closure notices, the trucker’s refused-return log, and gate timestamps. Recollection and email chains without timestamps generally fail.

Rebuild your chassis and per diem clocks

Send a quarter of drayage invoices with the interchange records. We reconstruct both clocks day by day against your contract free time and the terminal record, then file the variance. You only pay if we recover money.

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