How to Audit Your 3PL Invoice A Step-by-Step Guide (2026)

Build a simple two-column comparison: every distinct charge type on the invoice on the left, the corresponding contract rate on the right.

Three categories of findings will emerge immediately:

• Rate mismatches. You're billed $1.35/pick, the contract says $1.20. Small per-unit deltas produce five-figure annual leakage at scale.
• Uncontracted charges. Line items that don't exist in your rate card at all. “Technology fee,” “account management,” “compliance surcharge.” Every charge must trace to a signed rate.
• Rate drift. Charges that matched the contract a year ago but crept upward without a documented amendment. 3PLs update rate tables; notification emails get missed.

Flag everything without a clean match. This list is your audit backbone.

Rate accuracy means nothing if quantities are wrong. Pull your actual shipped order count from your commerce platform and compare it against the orders billed.

Watch for:

• Order count inflation. Billed orders exceeding shipped orders. Duplicate billing spikes during flash sales and peak season when systems strain.
• Unit count errors. Billed pick counts that exceed units actually shipped, often caused by cancelled or edited orders still flowing to billing.
• Returns double-billing. Return processing fees on orders where the return never physically arrived at the warehouse.

This step catches errors that a rate-card review alone never will, because the rate is correct. The quantity isn't.

Storage is the most commonly inflated category, because almost nobody verifies it.

Match the billed pallet, bin, or cubic-foot count against your month-end inventory snapshot. Common findings:

• Billed for pallet positions you vacated months ago
• Whole pallets billed for locations holding a partial carton
• Storage billed at “peak” rates outside the contractual peak window
• Re-palletization charges on inbound freight that arrived palletized

If billed storage doesn't reconcile to units on hand divided by realistic units-per-pallet, you have an audit point.

This is where the largest single-client recoveries come from, because the error is structural, not arithmetic.

The question isn't “is the pick fee correct?” It's “should this order have been billed as picks at all?” Examples we see repeatedly:

• Pre-packed cartons billed as individual picks. You ship master cartons that go out untouched, but the 3PL bills per-unit pick & pack instead of carton-in/carton-out rates. On a 36-unit carton, that's 36 pick fees where one carton fee belongs.
• First-unit vs. additional-unit confusion. Contracts typically price the first pick higher and additional units lower; billing systems sometimes charge the first-unit rate for every unit.
• B2B orders billed at DTC rates. Wholesale case-pick orders billed under your (more expensive) each-pick e-commerce rate structure.

If your product mix includes anything case-packed or wholesale, model what the invoice should have been under the correct logic. The gap is often the biggest number in your entire audit.

If your 3PL passes through shipping, verify the pass-through is honest:

• DIM weight errors. Lightweight items billed at dimensional weight because the warehouse used oversized packaging. This inflates shipping 15-40% on small products, and you're paying for their packaging decision.
• Markup beyond contract. Pass-through “plus 5%” that measures out to plus 12%.
• Accessorial padding. Residential surcharges on commercial addresses, address-correction fees preventable with clean data, Saturday-delivery fees on weekday deliveries.

Sample 20-30 shipments: compare the billed rate against the carrier's actual charge and your contracted markup.

Sort all remaining charges by dollar amount, descending. Anything vague (“special project,” “labor,” “supplies,” “handling”) needs a specific answer: what work, on what date, at what agreed rate, authorized by whom?

Legitimate 3PLs will have documentation. Charges that can't be substantiated become credits.

Compile every discrepancy into a single claims schedule: invoice number, date, line item, contracted rate, billed rate, quantity, and variance. Total it.

Then present it professionally. This matters, because the goal is recovery and a functioning ongoing relationship. A reputable 3PL will credit verified errors; the documentation quality determines how fast and how completely. Ask for three things:

1. Credits for the documented overcharges
2. Root-cause correction in their billing system (so the same error doesn't regenerate next month)
3. A written confirmation of the corrected rate logic going forward