Image: Pallets of USDA Emergency Food by U.S. Department of Agriculture, licensed under CC0 1.0.
A weight correction lands on a PRO you shipped three weeks ago. The bill of lading said 318 pounds, the carrier says 510, and the invoice is 140 dollars above what your system accrued. Your analyst checks that the carrier rated its own figure correctly, finds that it did, and releases the invoice.
Nobody pulled the certificate. The carrier's measurement happened at a named terminal, on a dated shift, on an identified device, and all of it was written down at the time. It is sitting behind credentials your team already has.
A correction is a claim, and claims come with paperwork
Carriers do not re-rate freight on a hunch. A reweigh or a redimension produces a record, and the larger carriers publish how to get it. XPO's Document Finder help page lists the document types retrievable by PRO number, and three of them are what a W&I dispute actually runs on: Weights and Corrections, Weights and Research Photos, and Inspection Report. NMFC Certificate sits in the same list. The published procedure runs to three steps: log in, open Document Finder from the Tools menu, enter the PRO numbers and the document type.
This is not only a portal feature. ShipEngine's LTL API documentation lists the documents that can be associated with a PRO number as bill_of_lading, delivery_receipt, invoice, or weight_inspection_certificate. The certificate is enumerated beside the BOL, which tells you how routine it is.
So the asymmetry most audit teams accept is not a shortage of evidence. The correction arrives as a dollar amount on an invoice line, the proof stays one lookup away, and nothing in the approval path forces the lookup.
What the certificate has to survive
Pull one and read it against the shipment you tendered. Five things decide whether the correction stands up.
| What the invoice line asserts | What the certificate has to show |
|---|---|
| This shipment weighed 510 pounds | A PRO and a piece count matching what left your dock, not a handling unit rebuilt at a crossdock |
| We measured it | A date, a terminal and an identified scale or dimensioner, rather than an unattributed figure keyed into a correction screen |
| The measurement is accurate | A device model carrying a current Certificate of Conformance |
| The variance justifies a re-rate | A delta that clears the tolerance written into the carrier's own rules tariff |
| The weight is yours | Gross and tare kept separate, so the skid, the slip sheet and the cage are not billed as product |
The third row is the one teams skip, and it has real standing behind it. NIST Handbook 44 Section 5.58 governs multiple dimension measuring devices, and its scope is devices used to determine the dimensions or volume of an object for the purpose of calculating freight, storage or postal charges. An instrument inside that scope is subject to type evaluation by the National Type Evaluation Program, run under the National Conference on Weights and Measures, which issues the certificate marking a model legal for trade. The dimensioner billing your freight is not a camera. It is a regulated measuring instrument with a certificate number, and asking which one is a fair question.
The tariff already drew the line for you
Tolerances are published, and they are tighter than most people assume. FedEx Freight's 100-Y rules tariff provides that where a reweigh comes back less than 50 pounds greater than the weight on the bill of lading, no reweigh fee applies and no change in linehaul charges will occur. At 50 pounds or more it applies a validation fee of 40 dollars, with freight, fuel surcharge and other applicable charges modified accordingly. The same tariff prices weighing on request under Item 990 at 155 dollars per shipment on the carrier's scale, or 419 dollars on a certified public scale.
AAA Cooper draws the boundary somewhere else. Its Item 970 applies a weigh fee when the variance exceeds 200 pounds, or is at least 50 pounds and more than 10 percent of the stated weight. The tariff adds that the same fee applies, at 25.30 dollars per shipment, when the shipper or consignee asks for a weigh or reweigh.
Two carriers, two thresholds, one consequence. Sixty pounds added to a 1,000 pound shipment clears the FedEx Freight line and triggers a re-rate. The same 60 pounds fails the AAA Cooper test, which wants the variance above 200 pounds, or at least 50 pounds and over 10 percent of the stated weight. Six percent is not over 10 percent. Whether a correction is even allowed to stand depends on the tariff governing that lane, and nobody reads it at approval time.
Two clocks, both statutory
Federal law gives the shipper a document right and gives both sides a deadline. Under 49 U.S.C. 13710(a)(1), a motor carrier of property, other than one providing transportation in noncontiguous domestic trade, shall provide to the shipper, on request of the shipper, a written or electronic copy of the rate, classification, rules and practices upon which any rate applicable to its shipment is based. Asking for the basis of a re-rate is not a favour.
Subsection (a)(3) sets the clocks. A carrier must issue any bill for charges in addition to those originally billed within 180 days of receipt of the original bill in order to have the right to collect them. A shipper must contest the original bill or a subsequent bill within 180 days of receipt in order to keep the right to contest. Balance due invoices from reweighs are precisely the kind of charge that shows up late, and the first question on one that appears seven months after the original bill is whether the right to collect survived the delay.
Where a regulator wrote the procedure out, the shape of a defensible reweigh is clear. Oregon's rule for the carriers it regulates, OAR 740-060-0080(4), requires the carrier to reweigh when the shipper asks before the delivery date, to disclose the certified scale, to furnish original or true copies of the weight tickets, and to bill on the lower of the two net scale weights. Interstate LTL does not run under that rule. It is still a useful benchmark, because it shows a regulator declining to bill on a figure that was neither documented nor shared.
What Penny does with a weight and inspection line
Penny treats a reweigh correction as a document request before she treats it as arithmetic.
Her first question is whether the certificate is on file. Where it is not, she retrieves it by PRO where the carrier exposes retrieval, and otherwise drafts the request citing 13710(a)(1) rather than letting the line pass as unverifiable. Silence in response is itself a finding, because a correction the carrier will not evidence is a correction it will struggle to defend.
She then tests the document against the shipment: PRO and piece count, date and terminal, the identified device, gross against tare, and whether the delta clears the tolerance in the governing tariff. Ordinary mistakes inside the carrier's own figures are common, and hardly anyone recomputes them.
Next she sets the certificate beside your tender record. Where your dock captured a measured weight and dimensions at the moment of loading, two contemporaneous records exist and there is a genuine dispute to argue, which is the position described in a dimension you never recorded. Where your side holds nothing, she does not manufacture a number. The line comes back marked needs-data with the missing field named, the behaviour set out in an agent that says needs data.
Last, she watches both clocks, flagging a late balance due bill and keeping your own contest window from quietly closing while a dispute sits in somebody's inbox.
What to do next
Take 90 days of LTL invoices and isolate every line carrying a weight or inspection correction. For each, answer one question: is the certificate attached to the file. Not available in principle, attached. The share where the answer is no is the share of corrections you paid on the carrier's word alone.
Then pull those certificates by PRO and run the five checks above. Expect a mix: some corrections are right, some measure a unit rebuilt after it left you, some sit under the tariff's own tolerance, and a few bill a skid as product.
Bring that 90 days to a walkthrough and we will run Penny across it live, retrieving the certificates and sorting the corrections into the ones you owe and the ones you do not.