Invoice Quantity Does Not Match Delivery: The Fix

If the invoice quantity does not match delivery, hold that line, do not pay it, and ask for a credit while the delivery is still recent. Your proof is the packing slip: it was written by the supplier at the moment the material left the counter or the truck, which makes it the one document in the chain that records what physically arrived. Count the invoice against it, line by line, once a week.

That is the whole check. It requires no software, no price history, no argument about what anything should have cost. Twelve on the invoice, ten on the slip, two short. It is the fastest-paying audit a contractor can run and most shops never run it, because the slip is in a truck and the invoice is on a desk and the two never meet.

So here is what you need: why the counts drift apart (mostly for boring, legitimate reasons), how to run the count in about ten minutes a week, the one trap that produces false alarms, and what to do when the packing slip does not exist.

Why the two numbers come apart

Almost none of this is anybody trying anything. It is what happens when an order is picked in one system, delivered by one person, and billed by another a week later.

Partial shipments billed in full. You ordered twelve, the branch had ten, the rest is on backorder. The picking ticket said twelve, the truck carried ten, and the billing run priced the order line rather than the shipped line. This is the single most common cause.

Split deliveries, one invoice. Material arrives across two days on two slips, then one invoice covers both. Now nobody can reconcile without both slips, and one of them is in a truck that went to a different job.

Substitutions with a different pack quantity. The counter is out of the exact SKU and sends the equivalent. Same job, same function, different bag count. Ten bags of 50 is not the same as ten bags of 100, and the invoice describes the substituted item while your memory describes the original.

Cut wire and made-to-order material. Cut goods are measured off a reel, and the measured length is what gets billed. It should match the slip. When it does not, that is worth catching, because cut wire is also the material most distributors will not take back at all: published return policies commonly give no credit on cut wire or made-to-order material. A cut-length error is money you cannot recover by returning anything.

Returns that never posted. You sent four back on Tuesday, the invoice still bills twelve. The return is a separate document moving on a separate timeline, and it is the most likely thing in this list to disappear entirely. That failure has its own post: the credit they promised and never issued.

Nobody counted at the jobsite. Material got dropped in a driveway and signed for by whoever was closest to the gate. The signature attests to nothing except that a truck came.

The count itself: four columns

Pull the week’s slips and the week’s invoices, sort by supplier, and build four columns per line. You can do this on a legal pad.

Three outcomes and three responses:

• Billed equals delivered. Pay it. Most lines land here and you should move past them fast.
• Billed is more than delivered. Hold the line, pay the rest of the invoice, request a credit for the difference. This is your money, and a quantity gap is a delivery question rather than a pricing one, so it gets chased at any dollar amount.
• Billed is less than delivered. Say something. It is the same control working in the other direction, and telling your branch about an undercharge on Monday is worth more at the next pricing conversation than a year of polite emails. It also makes the credit requests you send land completely differently.

That last point is not decoration. Quantity mismatch is a named failure mode in standard AP practice alongside price over tolerance, missing receiving documentation, wrong vendor, and misaligned line-item descriptions, and a customer who reports both directions is a customer whose counts get believed.

Unit of measure is where you will embarrass yourself

Before you send a single email, check the UOM column on both documents. This is the source of nearly every false alarm.

A box of 100 half-inch EMT set screw connectors can appear as quantity 1 on the packing slip (one box) and quantity 100 on the invoice (each), for exactly the same material at exactly the correct price. Wire can appear as 1 (one 250 foot roll) or 250 (feet). Fittings can be bagged in tens or fifties depending on which manufacturer the branch had on the shelf that morning.

So the real test is total units against total units, not quantity against quantity:

Slip quantity multiplied by slip pack size, compared against invoice quantity multiplied by invoice pack size.

Run that multiplication before you flag anything. A UOM mismatch on a line where the extended total is correct is a formatting difference, not an overcharge. A UOM mismatch where the extended total is wrong is a real error and usually a large one, because pack-size errors are off by a factor of ten or a hundred rather than by two.

What a short shipment is actually worth

Short shipments feel small line by line, which is why they get waved through. Do the arithmetic once and you will stop waving.

Say your invoice bills twelve boxes of a fitting at $8.00 and the slip shows ten. That is $16 on one line. Now say that happens on three lines a month across two suppliers. That is a few hundred dollars a year, and it is pure margin because you already paid for the labor.

The accounting version of this is the materials quantity variance, which is (actual quantity used minus standard quantity expected) times standard price. For estimators that formula is the bridge from a paperwork error to a job cost number: material you were billed for and never received shows up as a quantity variance on a job that did nothing wrong. The estimate was fine. The receiving was not.

The other cost is invisible and larger. When your billed quantities are wrong, your historical job costs are wrong, and next year’s bid is built off them. A shop that has quietly paid for phantom material for three years is bidding with three years of inflated material factors.

Running it in ten minutes a week

The failure mode is never the count. It is the collection.

1. Photograph every slip at the counter or at the tailgate, before the truck moves. Crumpled is fine. Blurry is not. If your crews only ever adopt one new habit, make it this one, and see how to handle paper supply-house invoices and tickets for making the photos usable.
2. Ask your branch to put the job number on the ticket. Their system has the field. This is what lets you match a slip to an invoice weeks later without remembering anything.
3. Batch on one morning. Slips sorted by supplier, invoices in the other hand, quantity column only. Do not check prices on this pass. Mixing the two checks is why the weekly review turns into a two-hour job and then stops happening.
4. Check the extended units, not the raw quantity. Pack size first, every time.
5. Mark three states per line: matched, short, or no slip. Nothing else.
6. One email per supplier, once a week. Not one per line.

Ten minutes is realistic for a shop running a handful of suppliers. It is not realistic if the slips are still in the trucks, which is why step one is step one.

When there is no packing slip

It happens constantly. Do not let a missing slip become the reason to abandon the check.

Escalate in order:

1. Ask whoever picked it up. A same-week memory from the foreman who loaded the van is real evidence, and it is often more precise than you expect.
2. Ask the branch for their copy. They keep signed delivery copies and will-call tickets, and most will email one within a day. Asking also tells them, gently, that you count.
3. Fall back to a two-way check. Compare the invoice to the PO or quote on quantity only, and mark the line unverified on delivery. Two-way matching is the recognized fallback when shipping receipts are not available. It proves you were billed what you ordered. It proves nothing about what arrived.
4. Pay it and mark the supplier. Three unverifiable lines from one branch in a month is a paperwork conversation with that branch, not a fight about $16.

Worth knowing for context: the formal version above three-way matching is four-way matching, which adds physical verification of the goods as a separate inspection step. A foreman counting boxes off a tailgate is, functionally, the four-way version. Contractors are often running the strongest form of this control and simply not writing it down.

The email that gets it corrected

Short, specific, no adjectives. The standard AP response to a mismatch is to withhold payment and request a corrected invoice or a credit note, and that is exactly what you are asking for.

Include five things: invoice number and line number, part number, quantity billed, quantity on the packing slip, and the slip number or delivery date. Attach the photo. Ask for a credit memo for the difference and say you are holding that line pending correction while paying the balance of the invoice.

That email is very hard to argue with, because you are not asserting anything. You are quoting the supplier’s own document back to them. If you would rather not write it from scratch each time, there is a copyable credit request email template.

Timing matters more than tone. Recent errors get corrected at the counter as routine business. Two-month-old ones get an explanation about how the period is closed. Weekly beats monthly for exactly this reason, and monthly beats never by a wide margin.

Where this fits in the bigger control

The quantity check is one leg of a longer chain: quote, purchase order, packing slip, invoice. It is the leg to start with because it is the only one that needs nothing but two pieces of paper and a working knowledge of counting. The full chain, including the price checks that need a history behind them, is laid out in the contractor invoice control process and in more depth for the middle three documents in three-way match for contractors.

One honest limitation. This check will never tell you that the price was wrong. Twelve billed, twelve delivered, at a unit price that has climbed 25% since March, passes cleanly. Quantity auditing and price creep detection are different jobs done with different evidence, and neither substitutes for the other.

The checklist

• Photograph every packing slip before the truck moves.
• Job number on every ticket, asked for at the counter.
• Weekly batch, sorted by supplier, quantity only on this pass.
• Compare extended units, not raw quantities. Check pack size first.
• Billed more than delivered: hold the line, pay the rest, request a credit memo.
• Billed less than delivered: tell them. It is worth more than it costs.
• No slip: ask the buyer, then ask the branch, then fall back to a quantity check against the PO and mark it unverified.
• One email per supplier per week, with the invoice number, line number, both quantities, and the slip photo attached.
• Watch for repeat short lines from the same branch. A pattern is a process problem on their end and gets fixed permanently once you name it.

Sources

• Stampli, 3-way invoice matching, two-way fallback and four-way physical verification
• Tipalti, 3-way match: named failure modes including quantity mismatch
• Bill.com, 3-way matching and the standard response to a mismatch
• Penn State, direct materials variances: the quantity variance formula
• Electrical Wholesalers, published return policy: no credit on cut wire or made-to-order material