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A three-way matching tolerance is the allowed difference between an invoice and its purchase order and receipt that your AP system will accept without flagging it for manual review. Instead of requiring an exact penny-for-penny match, you set a tolerance, say 5 percent or $25 on price and a small quantity variance, so minor, expected differences like rounding, shipping, or partial deliveries pass straight through. Anything outside the tolerance stops as an exception for a human to check. Tolerances are what make automated matching practical: without them, nearly every invoice would fail and defeat the purpose of automation.
This guide explains how matching tolerances work, how to set price and quantity tolerances sensibly, and the questions AP teams ask when configuring them.
What is three-way matching?
Three-way matching compares three documents before an invoice is paid: the purchase order (what you agreed to buy and at what price), the goods receipt (what you actually received), and the supplier invoice (what you are being billed). When all three agree, the invoice is legitimate and can be approved. When they disagree, something is wrong, a price change, a short shipment, a duplicate, or an error, and it needs review. Matching is the core control that stops you paying for goods you did not order or did not receive. For the full mechanics, see our guide to invoice matching software.
Why you need a tolerance
In the real world, an invoice rarely matches the PO to the exact cent. Freight and handling get added, prices shift slightly between order and delivery, currencies round, and shipments arrive in parts. If your system demanded a perfect match, almost every invoice would fail and land in a manual exception queue, which is exactly the manual work automation is supposed to remove. A tolerance tells the system: differences this small are normal and expected, so let them pass; differences bigger than this are worth a human look. Set well, tolerances let the majority of invoices flow through touchless while still catching the ones that matter.
Types of matching tolerance
There are two main dimensions you set tolerances on, and each can be expressed as a percentage, an absolute amount, or both.
| Tolerance type | What it controls | Typical setting |
|---|---|---|
| Price tolerance (percentage) | How far the unit or total price can differ from the PO | 1 to 5 percent |
| Price tolerance (absolute) | A flat dollar amount the difference cannot exceed | $10 to $50 per invoice |
| Quantity tolerance | How much the received or billed quantity can differ from the PO | 0 to 5 percent, or a unit count |
| Lower and upper limits | Whether the tolerance applies to over-billing, under-billing, or both | Usually tighter on over-billing |
Many teams combine a percentage and an absolute cap, so a difference must be within both, for example within 3 percent and no more than $25. That prevents a small percentage on a very large invoice from letting a big dollar variance slip through.
How to set matching tolerances
There is no single correct tolerance; it depends on your spend, your vendors, and your risk appetite. A few principles help.
Start tighter, then loosen with data
Begin with a conservative tolerance so you see most variances, then review what actually flows through your exception queue. If you find you are manually approving the same small, legitimate differences over and over, widen the tolerance to let them pass. Let the data, not a guess, set the number.
Tighten tolerances on high-value or high-risk spend
A 5 percent tolerance on a $500 invoice is $25; on a $500,000 invoice it is $25,000. Use tighter percentages or absolute caps on large invoices and on vendors with a history of errors, and looser ones on small, routine, trusted spend.
Watch over-billing more than under-billing
Being billed too much costs you money; being billed too little does not. Many teams set a tighter tolerance on over-billing than under-billing, so any overcharge outside a small band is always reviewed.
Keep clean PO data
Tolerances only work if the PO is accurate in the first place. Consistent, well-managed purchase orders are what let matching succeed automatically. Strong purchase order management upstream means fewer invoices fall out of tolerance for reasons that are really PO errors, not billing problems.
What happens when an invoice is outside tolerance?
When an invoice falls outside tolerance, the system flags it as an exception and routes it to a person to investigate rather than paying it automatically. The reviewer checks whether the difference is legitimate, such as an approved price increase or added freight, and either approves it, sends it back to the vendor, or requests a corrected invoice. This is the point of the whole control: the system handles the routine matches on its own and escalates only the genuine discrepancies, so your team spends its time where judgment is actually needed.
Frequently asked questions
What is a typical three-way match tolerance?
A typical price tolerance is 1 to 5 percent, often combined with an absolute cap like $10 to $50 per invoice, and a quantity tolerance of 0 to 5 percent. There is no universal standard; the right number depends on your spend size, vendor reliability, and risk appetite. Many teams tighten it on large or high-risk invoices and loosen it on small, routine ones.
What is the difference between two-way and three-way matching?
Two-way matching compares only the invoice and the purchase order. Three-way matching adds the goods receipt, confirming you actually received what you are being billed for. Three-way is the stronger control because it catches short shipments and goods never delivered, which two-way matching cannot see.
Should tolerance be a percentage or a dollar amount?
Both is usually best. A percentage alone can let a large dollar variance pass on a big invoice, while an absolute cap alone can be too strict on small ones. Combining them, requiring a difference to be within both a percentage and a dollar limit, gives you sensible control across invoice sizes.
Can matching tolerances be automated?
Yes. AP automation software applies your tolerances automatically on every invoice, passing matches within tolerance straight through and flagging only the exceptions. This is what enables touchless processing: clean, in-tolerance invoices never need a human, while out-of-tolerance ones are escalated for review.
Want to see automated matching with your own tolerances? Upload a real invoice into the workflow at the top of this page, then read our guide to the best AP automation software and how touchless invoice processing uses tolerances to eliminate manual review.