Audit your 3PL invoice line by line before you pay it
Updated · By Ecomsellertool editorial team
To audit a 3PL invoice automatically, load the billing detail behind the invoice, then check every line twice: against the rate in your contract and against the activity your own systems recorded, such as units received per receipt, orders shipped from Shopify or Amazon, and a storage snapshot. Rules compute the expected amount per line, and anything outside tolerance goes to a person to dispute.
- Amazon's 3PL pricing guide says storage is typically billed on the volume your inventory occupies, receiving is a flat or hourly rate, and picking is hourly or per item (checked October 30, 2026).
- ShipBob says storage is billed twice a month, on the 15th and the last day, prorated to the day, in bin, shelf or pallet locations (checked October 30, 2026).
- ShipMonk says its monthly minimum is set from your pick fees and projected order volume, and special projects are quoted before work starts (checked October 30, 2026).
- In this recipe fixed rules do every calculation; an AI model only reads PDF invoices, and a person decides every dispute and approves payment.
The step map: who runs each step
Trigger: The 3PL's monthly or twice-monthly invoice arrives, with its billing detail export, by email or in the 3PL's portal.
| Step | What happens | Who runs it |
|---|---|---|
| 1 | The invoice and its billing detail (the line-level export behind the totals) are captured from email or the 3PL portal, and the billing period is read from them. | Rule |
| 2 | When the detail only comes as a PDF, an AI model reads it into lines: charge type, quantity, rate, amount, and the order, receipt or location each line refers to. Lines it cannot read with confidence go to a person. | AI model |
| 3 | Rules pull your own records for the same period: receipts against ASNs and POs, orders and units shipped from Shopify, Amazon MCF and other channels, cancellations, returns received, label costs and the storage snapshot. | Rule |
| 4 | Each billed line is priced from the contract rate card with the audit table's formula, and its quantity is compared with your own record of the same activity. | Rule |
| 5 | Lines inside tolerance pass. Lines outside it, charges not on the rate card and duplicates are written to a dispute queue with the billed amount, the expected amount and the records behind both. | Rule |
| 6 | A person reviews each queued line, sends the dispute to the 3PL with the evidence, and records the answer: credit agreed, charge explained, or rate card updated. | Person |
| 7 | The invoice goes on to approval for payment with the disputed amount noted, and agreed credits are tracked until they show on a later invoice. | Person |
4 rule steps · 1 AI model step · 2 person steps. A rule follows fixed logic you approve; an AI model handles messy input and its output is checked by rules; a person makes the calls listed below.
What stays with a person
- Every dispute sent to the 3PL, and what counts as an acceptable answer
- Whether to pay the undisputed part now or hold the whole invoice, under your contract terms
- Tolerances per charge type, set by your finance lead
- Charges that are not on the rate card, such as a new fee or a special project with no approved quote
- Updating the rate card after a contract change, with the signed amendment on file
Which tools can run it
- A spreadsheet with the rate card, the 3PL's billing export and your order export, for one 3PL and a few hundred orders a month
- Zapier, Make or n8n with an AI model step that reads PDF invoices into a sheet, runs the checks and posts the queue to Slack
- Custom code on your accounts, for several 3PLs, label-level shipping checks, MCF and marketplace orders, and credit tracking
Systems it connects
- 3PL invoice and billing detail (portal export, CSV or PDF)
- 3PL contract rate card
- Receiving records, ASNs and purchase orders
- Shopify
- Amazon Seller Central (MCF orders)
- Shipping label data (carrier accounts or ShipStation)
- QuickBooks Online or Xero
- Slack or email for the dispute queue
Build size: Medium
The checks are simple arithmetic; the work is getting a line-level billing export, matching its references to your orders and receipts, and writing the rate card as data.
A 3PL invoice is easy to pay and hard to check. It arrives as a few totals, receiving, storage, fulfillment, shipping, with a long export behind them, and the month's orders have already shipped. If the bill creeps up a little each month, nobody can say whether that is growth, a rate change or a mistake. This recipe checks every billed line twice: once against the rate in your contract and once against what your own systems say happened. Only the lines that disagree reach a person. It is one page of our automation library.
Three neighbors do different jobs. Our supplier invoices to QuickBooks and Xero bills recipe books the invoice as a draft bill; this one decides whether the amount is right first. Our marketplace payouts recipe reconciles money coming in. And our finance and recovery agent runs this kind of billing check as one job among Amazon recoveries and fee audits; this page is the full build for the 3PL bill.
What should each 3PL charge be checked against?
Every line on a 3PL invoice is billed on some unit: a unit received, a location occupied, an order picked. Your own systems recorded the same activity. The audit table below pairs them, one row per common charge type. The tolerances are illustrative starting points; your finance lead sets the real ones. Copy the table, replace the rates with your contract's, and you can audit last month's invoice in a spreadsheet today.
| Charge | Billed on | Match it to (your record) | Expected amount | Illustrative tolerance | What goes to the reviewer |
|---|---|---|---|---|---|
| Receiving | Units, cartons, pallets or hours per receipt | Receipts against your ASN or PO, by receipt number | Billed unit count from your receipt × receiving rate | Count exact; amount within $1 | Receipts billed twice, counts above the ASN, receipts with no ASN |
| Storage | Bins, shelves, pallets or cubic feet, per period | Your storage snapshot on the 3PL's measuring date | Locations or cubic feet × rate, prorated by day if the contract says so | Location count exact; amount within 1% | Locations billed after they were emptied, a SKU moved to a larger location type |
| Pick and pack, first item | Orders shipped | Orders shipped from Shopify, Amazon MCF and other channels, net of cancellations | Orders shipped × first-item rate | Order count exact | Cancelled or duplicate orders billed, orders billed in the wrong period |
| Pick and pack, extra items | Additional units per order | Units shipped per order from your order lines | (Units shipped − orders shipped) × extra-item rate | Count exact | Kits or bundles counted as several picks when the contract bills one |
| Packaging and inserts | Boxes, mailers, inserts or fragile wrap per order | Packaging rule per SKU or order type | Count per packaging type × its rate | Count within 1% | Premium packaging billed on orders that use the standard rule |
| Shipping and postage | Labels | Label cost from your carrier accounts or shipping tool, by tracking number | Label cost + the contract markup, if any | Within $0.05 per label | Labels billed twice, labels on cancelled orders, markup above the contract |
| Surcharges | A rate or a percentage on another line | The surcharge clause in your contract | Base line × contract surcharge rate | Rate exact | Surcharges not in the contract, or applied to lines the clause excludes |
| Returns processing | Returns received | Returns received from your RMA or returns records | Returns received × returns rate | Count exact | Returns billed with no RMA, or billed twice |
| Monthly minimum | A floor on the month's fees | Total of the activity fees above | Minimum − activity fees, only if activity fees are below the minimum | Exact | A minimum charged on top of fees that already passed it |
| Special projects | Hours or units, per job | The quote you approved in writing | No more than the approved quote | At or below quote | Work with no approved quote, or billed above it |
| Account, software or other fees | A fixed monthly amount | The fee schedule in your contract | The contract amount, or zero if it is not listed | Exact | Any fee that is not on the rate card |
Write the rate card as data, one row per charge with its unit, rate, effective date and the contract clause it comes from. When the 3PL changes a rate, add a row with the new effective date instead of overwriting the old one, so last month's invoice is still checked at last month's rates. This is not legal advice; your contract and your lawyer decide what the 3PL may bill.
What does a month's audit look like?
An illustrative example, not a client result. A brand uses one 3PL with this rate card: receiving $0.30 a unit, storage $5 a bin, $10 a shelf and $40 a pallet a month on a month-end snapshot, pick and pack $3.00 for the first item and $0.50 for each extra item, a mailer $0.25 and a box $0.60, labels at cost with no markup, and kitting quoted per job. Its own records for the month show 4,800 units received on three ASNs, 3,100 orders and 4,650 units shipped, 2,000 orders in mailers and 1,100 in boxes, and a snapshot of 40 bins, 12 shelves and 18 pallets.
| Line (illustrative) | Expected | Billed | Difference | Why |
|---|---|---|---|---|
| Receiving | 4,800 × $0.30 = $1,440.00 | 5,600 × $0.30 = $1,680.00 | $240.00 | One 800-unit receipt billed twice |
| Storage | $200 + $120 + $720 = $1,040.00 | $200 + $120 + $880 = $1,200.00 | $160.00 | 22 pallets billed; the snapshot shows 18 |
| Pick and pack | 3,100 × $3.00 + 1,550 × $0.50 = $10,075.00 | 3,180 × $3.00 + 1,550 × $0.50 = $10,315.00 | $240.00 | 80 cancelled orders billed as shipped |
| Packaging | 2,000 × $0.25 + 1,100 × $0.60 = $1,160.00 | $1,160.00 | $0.00 | Matches |
| Shipping labels | $21,412.50 | $21,598.30 | $185.80 | Labels billed twice, found by tracking number |
| Account management fee | $0.00 | $150.00 | $150.00 | Not on the rate card |
| Kitting project | $480.00 (approved quote) | $480.00 | $0.00 | Matches the quote |
| Total | $35,607.50 | $36,583.30 | $975.80 |
Five lines go to the dispute queue, each with its evidence: the doubled receipt number, the snapshot's pallet list, the 80 cancelled order numbers, the duplicated tracking numbers and the contract's fee schedule. The reviewer pays $35,607.50 on time if the contract allows a partial payment, and disputes $975.80. In this example about a fifth of the gap is shipping, and no total would have shown it; only the label-level check by tracking number did.
How do 3PLs bill, according to their own pages?
Billing units differ by 3PL, which is why the rate card has to come from your own contract. Amazon's guide to 3PL pricing says storage fees are typically based on the volume your inventory occupies, in cubic feet or meters, that most 3PLs charge a flat or hourly rate for receiving labor, and that picking is typically charged hourly or per item, with packing sometimes bundled into other fulfillment fees (checked October 30, 2026).
Two large 3PLs describe their own rules. ShipBob's page on storage costs says storage is billed twice monthly, on the 15th and the last day of the month, prorated to the day, in bin, shelf or pallet locations, with each SKU in its own location (checked October 30, 2026). ShipBob's pricing page says shipping costs vary with weight, dimensions, destination and service, and that returns carry a flat fee applied when the return arrives (checked October 30, 2026).
ShipMonk's pricing page says its monthly minimum is set from your pick fees and projected order volume, that custom packages are billed as an additional item during pick and pack, that fragile wrapping costs extra, and that special projects are quoted before work starts (checked October 30, 2026). Each of those rules becomes a row in your rate card: a twice-monthly prorated storage rule needs two snapshots a month, and a quoted project needs the approved quote on file before the invoice arrives.
Where does the data for the audit come from?
The 3PL's side is the billing detail: the line-level export behind the invoice, from its portal or by email. Ask for it as a CSV with an order, receipt or location reference on every line; that one request does more for the audit than any tool. If it only comes as a PDF, this is where an AI model helps, reading the lines into a table. It never decides whether a line is right.
Your side comes from systems you already run. Orders and cancellations come from Shopify, and from Amazon when the 3PL ships marketplace orders; our Shopify orders to 3PL and Amazon and Walmart orders to 3PL recipes keep the order IDs that make this match possible. Receipts come from your ASNs and POs. Label costs come from your carrier accounts or shipping tool. The storage snapshot is the hard one: take it yourself on the 3PL's measuring dates. Matching stock counts between the 3PL and Amazon FBA is a separate job, covered on our 3PL reconciliation page.
What happens after a line is flagged?
The dispute queue holds one row per flagged line: billed amount, expected amount, difference, the records behind both, and a drafted note to the 3PL. A person sends it, so the tone and timing stay with your team and the relationship. The answer is recorded on the row. A credit agreed is tracked until it appears on a later invoice, because a promised credit that never shows up is the same leak a month later.
Some answers change the audit, not the invoice. If the 3PL shows a signed amendment with a new rate, the rate card gets a new row from that date. If a charge was right because your snapshot was late, the snapshot rule is fixed. Approved credits and the final amount then flow to the bill in QuickBooks Online or Xero. Lost or damaged parcels are a different claim, against the carrier; our carrier claims recipe covers that.
Which tool should run it?
| Level | Fits when | What to watch |
|---|---|---|
| A spreadsheet with the rate card, the billing export and your order export | One 3PL, a few hundred orders a month, a CSV billing export | Someone must load the exports every month; storage snapshots are easy to forget |
| Zapier, Make or n8n with an AI model step | PDF invoices, one 3PL, alerts to Slack | Matching thousands of lines can hit task limits; log every run |
| Custom code on your accounts | Several 3PLs or warehouses, label-level checks, marketplace and MCF orders, credit tracking | Can run on Ecomsellertool Growth OS beside your order and inventory data |
Our Zapier vs Make vs n8n comparison covers how each tool counts work. If you are still choosing how to fulfill, our MCF vs WFS vs 3PL guide compares the options. If you run the warehouse and bill brands yourself, our page for 3PLs and prep centers is the other side of this invoice.
Who builds 3PL invoice audits?
Ecomsellertool builds workflow automation on your own store, 3PL and accounting accounts; we have built software on Amazon's seller APIs since 2017. For a 3PL audit we write your rate card and audit table with you first, then connect the billing export, your order and receipt data, the checks and the dispute queue. Send a project brief below, or read how our workflow automation service works.
The building blocks are work we have shipped:
- Expected fees computed, not just read. For Seller-Drive we built a fee calculation engine that computes fees Amazon does not provide, from predefined criteria and business rules, and shows them beside the fees Amazon reports, so sellers see their true cost structure. The engine adapts its calculations when fee structures change.
- Billing from the warehouse side. For Pacific Prep, a prep and ship company, we built a warehouse system covering receiving, bin locations, inventory, shipping and a billing module that keeps detailed records of the transactions and activities relevant to billing.
Get your 3PL invoice audit built
Send us your 3PL invoice and rate card
Describe the workflow you want automated. We reply with a written plan: scope, timeline and a fixed price.
Frequently asked questions
How do I audit a 3PL invoice?
Ask the 3PL for the billing detail behind the invoice, not just the summary. Price each line from your contract's rate card, compare each quantity with your own records of receipts, orders shipped, returns and storage, and list every line where the billed amount and the expected amount differ by more than your tolerance.
What are the most common 3PL billing errors?
Look first at lines that can be counted twice or never stop: receipts billed twice, cancelled orders billed as shipped, storage locations still billed after they were emptied, labels billed twice, a minimum fee charged in a month when activity fees already passed it, and fees that are not in the contract at all.
How do I check 3PL storage charges?
Take a storage snapshot of your own on the same date the 3PL measures, with the number of bins, shelves and pallets, or the cubic feet, per SKU. Multiply by the contract rate, prorate by day if your 3PL does, and compare. Ask for the location list behind any storage line that does not match.
Should I pay a 3PL invoice while a dispute is open?
That depends on your contract. One option is to pay the undisputed part on time and hold only the disputed lines, if the contract allows it. Read the payment and dispute terms in your agreement, and ask your lawyer if they are unclear; this is not legal advice.
Can AI audit 3PL invoices?
An AI model is useful for one step: reading PDF invoices into lines. The audit itself should be fixed rules, because the expected amount is plain arithmetic from the rate card and your records. A person still decides every dispute.
How is this different from turning invoices into bills in QuickBooks or Xero?
The bills workflow books an invoice and matches it to a purchase order and a receipt. A 3PL invoice has no purchase order, so this recipe checks it a different way, line by line against the rate card and your activity, before the bill is approved.
