By KYN AI Advisory Team — AI implementation specialists, Singapore
An SME handling 200 invoices a month should match each supplier invoice to a purchase order or agreed quote and to proof of delivery, accept differences within a written tolerance, and send everything else to a named person. At 200 a month, manual checking costs days of staff time and misses duplicates. A rules-based workflow captures the invoice, matches it, and queues exceptions, while a person approves payment. This guide sets out the steps, the numbers to set and the controls.
What is invoice reconciliation?
Invoice reconciliation is the check that an invoice you are about to pay matches what you ordered and received. For accounts payable, it protects against paying twice, paying the wrong amount and paying for goods that never arrived. For accounts receivable, it means matching invoices you issued to payments received.
This article focuses on payables, which carry the larger error risk. Receivables reconciliation is covered in bank reconciliation basics.
Why is 200 a month a turning point?
Take 200 invoices. If a person spends 5 minutes on each to key it in, find the order, check the amount and file it, that is about 17 hours a month. Add queries to suppliers and corrections, and it is easily two working days. Those figures are our arithmetic from an assumed 5 minutes, not a measured benchmark; time your own team for a week.
Volume creates three problems at this size.
- Duplicates. The same invoice arrives by email and by post, or a supplier resends it. A person checking 200 documents will not remember all of them.
- Delay. Invoices wait in one inbox for the one person who knows the supplier.
- Inconsistency. Different people apply different tolerances and codes.
Below about 30 invoices a month, a spreadsheet and discipline are enough. Above 200, the process needs rules.
What is a three-way match?
A three-way match compares three documents:
- Purchase order or agreed quote: what you asked for and at what price.
- Goods receipt or delivery note: what arrived, or confirmation that the service was done.
- Supplier invoice: what the supplier says you owe.
Pay only when the three agree on supplier, items, quantity and price, within tolerance. Services often have no delivery note. Use a two-way match against the quote and a named approver who confirms the work was done.
What tolerance should you set?
A tolerance is the difference you accept without review. Set it in writing and apply it the same way every time.
| Difference | Suggested rule | |---|---| | Exact match | Approve automatically for payment run | | Within a small amount, for example S$5 | Approve, log the difference | | Above the small amount, below a review amount | Route to the budget owner | | Above the review amount | Route to a manager | | Missing order or receipt | Hold; ask for the document | | Duplicate suspected | Hold; compare to the earlier invoice |
The numbers in this table are examples. Your finance lead sets them, based on your average invoice and your margin. Review them each quarter against the exception list.
The workflow, step by step
- Capture. Invoices arrive in one shared mailbox or upload point. An agent reads each and extracts supplier, invoice number, date, currency, amounts, tax and line items.
- Identify the supplier. Match the name and tax registration number to your supplier list. Unknown suppliers go to a person for approval before the first payment.
- Check for duplicates. Compare supplier, invoice number, amount and date to prior invoices.
- Find the order. Match by order number on the invoice, or by supplier and amount if there is none.
- Compare. Check quantity, price, tax and total against the order and receipt.
- Apply tolerance. Auto-approve within tolerance. Route the rest by rule.
- Code. Propose the expense account and tax code from the supplier's history.
- Queue for payment. Approved invoices go to the payment run, which a named person releases.
- Log. Record every step, the actor and the evidence.
What exceptions should you expect?
In the first month, expect a larger exception list than you want. The causes are usually data, not the matching.
- Suppliers whose names differ across documents.
- Orders raised verbally and never recorded.
- Partial deliveries invoiced in full.
- Price changes agreed by phone.
- Tax shown differently on the quote and the invoice.
- Foreign-currency invoices where the rate differs. See recording foreign currency expenses.
Fix the cause upstream where you can. A rule that all orders go through one form removes most of the second item.
How do you measure it?
Track these monthly.
- Straight-through rate. Invoices approved without a person touching them, divided by all invoices.
- Exception age. Median days an exception stays open.
- Duplicates caught. Count and value.
- Late payments. Invoices paid after their due date.
- Cost per invoice. Staff time plus software, divided by invoices.
Start with the baseline from one manual month. Without it, you cannot say whether the change helped.
What controls does payment need?
- Nobody who approves a payment can also add a supplier or change bank details.
- Changes to supplier bank details need a call-back to a known number, by a person.
- The agent never releases payment. A named person does.
- Every approval is logged with the actor and the time.
- Month-end cut-off applies to invoices received but not yet approved. They are accrued.
Fraud often arrives as an invoice with changed bank details. An agent can flag a changed account against history. A person confirms it.
How do you roll this out in four weeks?
- Week 1: baseline. Count invoices, time a sample, list suppliers and record duplicates found in the last quarter.
- Week 2: clean the supplier list. One record per supplier, with tax registration number, bank details and payment terms. Remove inactive entries.
- Week 3: run in parallel. The workflow processes the month's invoices alongside the manual process. Compare outcomes and note every disagreement.
- Week 4: switch the low-risk lane. Exact matches and recurring suppliers go through the workflow. Everything else stays manual until its exceptions fall to an acceptable level.
Keep the manual route for new suppliers and large invoices for the first quarter. Widen the automated lane only when the exception list is short and the reasons for each exception are understood.
Where KYN fits
KYN builds invoice capture and matching in the client's own cloud account. In our own books, bills arrive from Gmail, the system extracts the fields and queues what it cannot place. For a manufacturer, we moved 10,210 vendor quotes into one system so that invoices could be matched to quotes. Money and postings wait for a named person, and every action is logged with the actor. See finance systems and integrations.
KYN starts with a 14-day review: we list your tools and interview the people who key, check and approve invoices. A full build ships in under 90 days. Pricing is a one-off build fee, then a monthly retainer of at least twelve months, quoted after the review.
Frequently asked questions
Do I need a purchase order for every invoice?
No. Recurring services such as rent, utilities and subscriptions can match to a contract or a standing rule. Use purchase orders where price and quantity vary, and a named approver for the rest.
Can an agent approve invoices for payment?
It can approve within a written tolerance to place an invoice in the payment queue. Releasing the payment stays with a named person.
How do I stop duplicate invoices?
Check supplier, invoice number, date and amount against all prior invoices at capture, and treat near matches as suspected duplicates for a person to compare. Also record the document hash so the same file cannot enter twice.
Checked 30 October 2026.
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