Vendor invoice processing is the sequence a bill follows between arriving and being paid: receive it, capture its details, code it to an account, match it to what was ordered and delivered, approve it, pay it and record the payment. Each step leaves a document behind, and each has an owner and a check that stops errors moving forward.
The vendor invoice processing steps in an accounts payable workflow
An accounts payable workflow, often shortened to AP workflow, moves each vendor invoice through seven steps: receive, capture, code, match, approve, pay and record. The order matters. Coding before capture invites typing errors into the books, and paying before approval removes the one check meant to stop a wrong bill.
Receive. The invoice arrives by email, post, portal or a photo from the client. Receiving means getting it into one known place with the date it came in. A bill sitting in someone's personal mailbox has not been received in any useful sense. Setting up a single intake address is covered in the post on setting up one inbox for a client's vendor invoices.
Capture. Someone, or software, reads the vendor, invoice number, dates, amounts and line items into the books or a sheet. This is the step where most typing errors start.
Code. Each invoice, or each line on it, is assigned to an expense or asset account, and to a class, location or job if the client tracks them.
Match. The invoice is compared with what the business ordered and what it received. For businesses that issue purchase orders, this is three-way matching, explained in the next section.
Approve. A person with authority confirms the bill should be paid. Approval is evidence that someone looked, so it should leave a trace: an initial, an email reply or a status in the system.
Pay. The bill is paid by check, transfer or card on or before its due date.
Record. The payment is entered against the open bill, the bill is closed, and the paid invoice is filed with its proof of payment. IRS Publication 583 explains why both matter: its section on supporting documents lists invoices among expense records and says that proof of payment alone does not establish a deduction, so invoices should be kept to show the cost was incurred. How long those records are kept is covered in how long receipts should be kept for taxes.
The step table
The table below summarizes the workflow for a small business whose books a firm keeps. The owners shown are typical, not fixed, and shift with the engagement.
| Step | Document produced | Usual owner | Control that applies |
|---|---|---|---|
| Receive | Invoice file with a received date | Client, or firm via a shared inbox | One intake point; no bills left in personal mailboxes |
| Capture | Bill entered in the books or a sheet | Firm bookkeeper | Totals checked against the invoice; duplicate check |
| Code | Account and class on each line | Firm bookkeeper | Coding reviewed against prior bills from the vendor |
| Match | Matched PO, receiving record and invoice | Client staff | Quantities and prices agree within an agreed tolerance |
| Approve | Approval note or status | Client owner or manager | Approver is not the person who entered the bill |
| Pay | Check, transfer or card record | Client, sometimes firm | Payment matches an approved bill; vendor details unchanged |
| Record | Closed bill with proof of payment | Firm bookkeeper | Payment ties to the bank statement |
What is three-way matching in vendor invoice processing?
Three-way matching compares three documents before a vendor invoice is approved: the purchase order, which says what the business agreed to buy; the receiving record, which says what actually arrived; and the invoice, which says what the vendor is charging. When item, quantity and price agree across all three, the bill moves to approval.
Each pair answers a different question. The purchase order against the invoice asks whether the vendor charged the agreed price. The receiving record against the invoice asks whether the business is paying for goods it received. A bill that passes one comparison can fail the other: the price is right but only eight of ten boxes arrived.
Businesses that do not issue purchase orders use a lighter version. A two-way match compares the invoice with the order or contract, without a receiving record. Services such as cleaning or consulting often have no receiving record at all, so the check becomes a manager confirming the work was done.
A tolerance keeps matching practical. Freight, rounding and small price changes mean the three documents rarely agree to the cent. A business can set a rule, for example any difference under a set dollar amount or percentage is accepted, and anything above it goes back to the buyer. Write the tolerance down so every bookkeeper applies the same one.
For most small clients of an accounting firm, formal three-way matching is rare. The useful habit to borrow is the second question: did the client receive what this bill charges for?
Who owns each vendor invoice processing step, the client or the firm?
When a firm does a client's bookkeeping, vendor invoice processing usually splits down the middle. The client receives bills, confirms goods arrived, approves and pays. The firm captures, codes and records. The split works because the decisions about spending and paying stay with the business that owns the money.
The split shifts with the engagement. A firm that only reconciles monthly may see invoices for the first time at month-end, after they are paid, and its work is capturing and recording. A firm that runs bill pay for a client may handle receiving, capture and payment scheduling, with the client approving each payment run. Write down which steps the firm owns in the engagement letter or a short procedures note, so nobody assumes the other side did a step.
As an example, take a fictional landscaping company, Example Grounds LLC, whose books a firm keeps. The owner's office manager forwards every bill to a shared inbox and confirms deliveries against the supplier's packing slips. The firm saves and enters the bills each week, codes them, and sends the owner a list of bills due in the next ten days. The owner replies to approve, pays from the bank's website, and the firm records each payment when it reconciles the account at month-end.
Approval and payment are the two steps a firm should be most careful about taking over. If the same person can enter a bill, approve it and release the payment, no second person ever sees it. Where a firm does schedule payments, the client's approval should come before the payment run, not after.
Vendor invoice exceptions: credit memos, partial shipments and disputes
Vendor invoice exceptions are bills that cannot follow the normal sequence from receipt to payment. Credit memos reduce what is owed, partial shipments bill for part of an order, disputed invoices are held while a question is settled, and revised invoices replace earlier ones. Each needs its own handling so the books show what the client truly owes.
Credit memos. A credit memo reduces the balance owed to a vendor, usually for a return, a damaged item or a billing error. It should reference the invoice it relates to. Record it as a separate document against the vendor and apply it to the right open bill, rather than editing the original invoice.
Partial shipments. A vendor may invoice for six of ten items now and the rest later. The receiving record shows six, the purchase order shows ten. Match the invoice to what was received and leave the order open for the remainder.
Disputes. A bill for the wrong price, the wrong quantity or work not done is put on hold. Mark it as disputed, note who is talking to the vendor, and keep it out of the payment run until it is settled. A disputed bill that stays open without a note is the one paid by mistake three weeks later.
Revised invoices. A vendor may reissue an invoice with a corrected amount, sometimes with the same number. Void the original and enter the revision; do not pay both.
Statements and reminders. A vendor statement or overdue reminder is not a new bill, even though it carries amounts and often the original invoice. Check it against open bills instead of entering it.
Controls a bookkeeper should check in vendor invoice processing
Controls in vendor invoice processing are the checks that stop wrong, duplicate or fraudulent bills from being paid. Three matter most for a small business: no single person controls a bill from entry to payment, every approval leaves evidence, and any change to a vendor's payment details is confirmed before money moves.
Separate the duties. The person who enters bills should not be the only person who approves them, and neither should be able to change vendor bank details alone. In a two-person office, full separation may not be possible. The owner reviewing the payment run and the bank statement each month is a reasonable substitute.
Keep approval evidence. An approval that happened in a hallway cannot be checked later. An email reply, an initial on the invoice or a status in the accounting system all work, as long as they show who approved and when.
Confirm vendor master changes. The vendor master is the list of vendors with their names, addresses, tax IDs and bank details. A request to change a vendor's bank account, especially by email, should be confirmed by calling the vendor on a number already on file. Vendor tax details collected for information returns are covered in the post on W-9 collection.
Check for duplicates before payment. The same invoice can arrive twice through different routes. Matching vendor, invoice number, date and amount before paying catches most of them.
Software can take over some of this work, mainly capture and the duplicate check. Which steps it can handle and which stay with a person is the subject of the post on what accounts payable automation covers, step by step. The case for automating invoice entry is set out in invoice automation, and the wider picture across tax forms and statements in accounting document automation.
For a firm, Schema CPA handles the capture end of this sequence: it reads each client's vendor invoices, flags a bill that arrives twice, and exports the details to Excel or CSV. Approval and payment stay with the client. The hours calculator on the Schema CPA homepage estimates what manual entry costs a firm today, from its own client and document counts.