What Does Each Supplier Invoice Cost You?
Every invoice that arrives by email gets opened, read, keyed into the accounting system, coded to an account and checked against a purchase order. Eight minutes each does not sound like much until it is four hundred invoices a month. This calculator turns your own volumes into a monthly and annual cost, then shows what is left once AI capture handles all but the exceptions.
Use real numbers from last month. Count invoices from the accounting system, and time three invoices from opening the email to saving the entry rather than guessing.
Invoice Processing Cost Calculator
Last month’s real numbers. Count them, time them, then adjust the exception rate.
Count from the accounting system, not from memory.
From opening the email to saving the entry. Time three real ones.
Loaded cost including super and leave, roughly 1.3x base pay.
Share of invoices later corrected: wrong amount, supplier, code or duplicate.
Blend of quick recodes and the occasional recovered duplicate payment.
Share of invoices AI capture sends to a person. Start high and test lower.
Labour plus error correction. Chasing approvals and supplier queries are extra.
Labour and error correction only. The AI capture figure costs the exception share at your existing minutes, hourly rate and error rate, and excludes software subscription and setup. Compare the gross annual saving against a quote, or use the payback period calculator.
What the Four Results Mean
The headline figure is the monthly cost of processing invoices by hand, labour plus error correction. The other results break that down and show the same process with AI capture doing the first pass.
Hours consumed
Invoices per month multiplied by minutes per invoice, divided by sixty. This is the time your accounts payable person, or the office manager doing it between other jobs, spends on pure keying. It excludes chasing approvals and dealing with supplier queries, both of which come on top.
Error cost
Keying errors are part of the cost of manual processing, not a separate problem. A wrong amount, a wrong supplier or a wrong account code gets found later, usually at reconciliation or when a supplier calls about a short payment. The error rate and cost per error you enter drive this figure.
Cost with AI capture
AI capture reads the invoice, extracts the fields, matches the supplier and proposes the coding. Invoices it is unsure about go to a person. The exception rate you set is the share still handled manually, costed at the same minutes and error rate as today. Software cost is not included, so compare this figure against a quote.
How the Numbers Are Built
Four steps, all shown so you can check them in a spreadsheet. Nothing is assumed beyond what you enter.
Labour cost per month
Invoices per month, multiplied by minutes per invoice, divided by 60, multiplied by the hourly cost of the person doing the work.
Error cost per month
Invoices per month multiplied by your error rate gives the number of errors. Each error is multiplied by the cost you enter to find and fix it.
Total and annualise
Labour plus error cost is the monthly figure. Multiplied by twelve it becomes the annual cost. Hours are annualised the same way.
Apply the exception rate
With AI capture, only the exception share of invoices is keyed by a person. That share is costed at your existing minutes, hourly rate and error rate. The difference, times twelve, is the gross annual saving before software.
Where Invoice Processing Time Actually Goes
Eight minutes per invoice surprises people until they watch someone do it. The time is spread across small steps, and each one is a place an error can be made.
Finding and reading the invoice
Invoices arrive as PDF attachments, as links to supplier portals, as photos from a site phone and occasionally on paper. Before anything is keyed, someone opens the email, works out which entity it belongs to, checks it is not a duplicate of a statement or a reminder, and finds the purchase order if there is one.
- Multiple entities or cost centres multiply the sorting step
- Supplier portals add a login and a download to every invoice
- Duplicate detection is done from memory, which is where duplicates slip through
- Photos and scans take longer to read than native PDFs
Keying and coding
Supplier, invoice number, date, due date, line items, GST and totals are typed into the accounting system, whether that is Xero, MYOB or an ERP. Then each line is coded to an account and often a tracking category or job. Coding is where experienced staff earn their rate and where new staff make most of the errors.
- Line-item invoices take several times longer than single-line ones
- Account coding rules live in someone’s head unless they are written down
- GST treatment varies by line and is a common correction at BAS time
- Supplier records with inconsistent names cause mismatches and duplicates
Matching, approval and exceptions
Where a purchase order exists, the invoice is matched against it and any variance goes back to the person who ordered. Where it does not, the invoice goes to an approver by email. Both paths involve waiting, chasing and re-opening the invoice later, none of which shows up in the keying time.
- Three-way matching (order, receipt, invoice) is slow by hand and exact by machine
- Approval by email means the invoice is handled at least twice
- Variances are the true exceptions and should stay with a person
- The exception rate in the calculator is where these cases land
Choosing an honest exception rate
The exception rate is the most important input in the AI figure and the easiest to get wrong. Start high. A new deployment sends more to people while supplier formats are learned and coding rules are refined. The rate falls as recurring suppliers are recognised, but it never reaches zero, because some invoices genuinely need a decision.
- Recurring suppliers with consistent layouts are handled first and best
- One-off suppliers and handwritten invoices stay in the exception queue
- Set the confidence threshold so the system asks rather than guesses
- Rerun the calculator at a higher rate to see the downside case
Next Steps
AI Invoice Processing
How capture, matching and coding work in practice, and where a person stays in the loop.
See how it works →Automation Payback Period Calculator
Put a setup cost and monthly fee against the saving above and see when it breaks even.
Work out payback →AI Purchase Order Automation
Matching invoices to orders is easier when the orders are structured too.
See purchase orders →Frequently Asked Questions
What should I include in minutes per invoice?
Everything from opening the email to saving the entry in the accounting system: reading the invoice, checking for a duplicate, finding the purchase order, keying the header and lines, coding each line and attaching the PDF. Do not include waiting for an approver, since that is elapsed time rather than labour. Time three real invoices of different types and use the average. Single-line invoices from a regular supplier can take two minutes. A multi-line invoice from a new supplier with a job code on each line can take twenty.
How do I find my error rate?
Look at the corrections made in the last month or two. Credit notes raised against your own entries, journals correcting account codes, supplier statements that did not reconcile, and duplicate payments recovered are all evidence of an error that was made and found. Divide the count by the invoices processed in the same period. If you have no way to count corrections, that is itself worth knowing, and a rate of a few per cent is a reasonable starting point to test against.
What is a realistic cost per error?
It depends on where the error is found. An account coding error caught at month end costs a few minutes of a bookkeeper’s time. A wrong amount that is paid, then recovered from a supplier, costs an hour of correspondence and sometimes a relationship. A duplicate payment that is never recovered costs the full invoice. Use a blended figure that reflects your own mix, and if you are unsure, run the calculator at two values to see how much it matters to the result.
Does the AI capture figure include software cost?
No, deliberately. Software pricing varies by volume and by how much matching and approval workflow is included, so putting a single figure in would be a guess. The calculator shows the labour and error cost that remains once AI handles all but the exceptions. Compare the gross annual saving against an actual quote, or take it to the payback period calculator on this site to test a setup cost and monthly fee against it.
Why does the exception share still carry an error rate?
Because the invoices a person still handles are keyed the same way they are today, by the same people under the same conditions. Assuming those entries are suddenly error-free would flatter the result. If anything, exceptions are the harder invoices, so the true rate on them may be higher. The calculator uses your existing rate for them, which is the conservative choice.
Is this only useful for large accounts payable teams?
No. The calculation works at any volume. A business processing eighty invoices a month through an office manager who also answers the phone has a real cost, even if it is not a full-time role. The question at low volume is different: the saving is smaller in dollars, but the time returned to a person with other responsibilities is often worth more than the figure suggests. Enter your actual numbers and judge the result against what that person would otherwise do with the hours.
Sources and further reading
- Xero API documentation (Xero)
- MYOB business software (MYOB)
Know Your Cost per Invoice Now?
Send us your monthly invoice count and where they come from. We will tell you what exception rate to expect for your supplier mix and quote against the saving you just calculated.