Accounts Payable for Buyers: Invoice Matching, Approval and Payment

A buyer’s work does not end when the purchase order is sent or the supplier delivers the goods. The purchase must also be completed financially.

For the supplier to be paid correctly and on time, the invoice must match what was ordered, delivered and accepted. When information is missing or incorrect, the invoice may be blocked. This often leads to questions involving the buyer, supplier, receiving function and Accounts Payable.

Buyers do not normally execute supplier payments. That responsibility usually belongs to Accounts Payable or Finance. However, the buyer strongly influences whether an invoice can be processed correctly.

In this article, you will learn how Accounts Payable connects to procurement, how invoices are matched and approved, and what buyers can do to prevent payment delays and supplier disputes.

Procurement framework

Primary role: Operative procurement
Supporting roles: Tactical procurement and procurement management
Process: Procure-to-pay, invoice matching, approval, exception handling and payment
Learning level: Basic
Related course: Basics for an Operative Buyer

Quick answer: What buyers need to know about Accounts Payable

Accounts Payable receives, checks and processes supplier invoices for payment.

The buyer does not normally make the payment, but the buyer helps create the conditions for correct payment. Accurate purchase orders, registered deliveries, agreed payment terms and timely handling of invoice differences all make the Accounts Payable process work more efficiently.

A useful principle for buyers is:

Accounts Payable processes the invoice, but procurement influences whether the invoice can be processed correctly.

What is Accounts Payable?

Accounts Payable, often abbreviated as A/P or AP, is the function responsible for managing the amounts a company owes to its suppliers.

Typical Accounts Payable activities include:

• receiving supplier invoices;
• checking invoice information;
• matching invoices against purchase orders and delivery records;
• routing invoices for approval;
• investigating invoice differences;
• preparing approved invoices for payment;
• recording payments;
• reconciling supplier accounts;
• maintaining documentation for audit and financial control.

Accounts Payable works closely with procurement, receiving functions, budget owners, accounting and suppliers.

Although procurement and Accounts Payable have different responsibilities, they are connected through the procure-to-pay process.

How procurement and Accounts Payable work together

Procurement creates or influences the commercial conditions of the purchase. These conditions include:

• what is being purchased;
• quantity;
• price;
• currency;
• delivery terms;
• payment terms;
• freight and additional charges;
• invoicing instructions;
• purchase-order requirements.

Accounts Payable uses this information when processing the supplier’s invoice.

When the information on the purchase order, delivery record and invoice is consistent, the invoice can normally be processed efficiently. When the information does not match, Accounts Payable may need help from the buyer or another responsible person.

Typical questions sent to a buyer include:

• Did procurement agree to this price?
• Was the additional freight charge approved?
• Has the full quantity been delivered?
• Has the service been completed and accepted?
• Is the invoice connected to the correct purchase order?
• Should the invoice be approved, rejected or corrected?
• Does the supplier need to issue a credit invoice?

The buyer should respond promptly and base the response on the purchase order, contract, delivery documentation or another recorded agreement.

Where Accounts Payable fits in the procure-to-pay process

Accounts Payable is part of the procure-to-pay process.

A simplified process is:

1. A need is identified.
2. A purchase requisition is created and approved.
3. A purchase order is issued.
4. The supplier confirms the order.
5. The goods or services are delivered.
6. A goods receipt or service acceptance is registered.
7. The supplier sends an invoice.
8. The invoice is matched against purchasing and delivery information.
9. The invoice is approved automatically or manually.
10. Any differences are investigated and resolved.
11. The approved invoice is paid according to the agreed payment terms.
12. The transaction is recorded and stored.

The buyer is not responsible for every step. However, the quality of the purchasing information affects the full process.

A missing purchase-order number, an incorrect price or an unregistered goods receipt can prevent an otherwise valid invoice from being paid.

What information should a supplier invoice contain?

The exact statutory requirements for an invoice depend on the country, tax jurisdiction and type of transaction. Companies may also have additional internal requirements.

A correct and processable supplier invoice will normally include:

1. Supplier information
   The supplier’s legal name, address and contact information.
2. Unique invoice number
   A reference that identifies the individual invoice.
3. Invoice date
   The date on which the invoice was issued.
4. Customer information
   The correct legal name and invoicing address of the buying company.
5. Purchase-order reference
   The purchase-order number and, when required, the relevant purchase-order line.
6. Description of the goods or services
   A clear description of what is being invoiced.
7. Quantity and unit price
   The invoiced quantity, unit of measure and agreed price.
8. Currency
   The currency in which the invoice is issued and should be paid.
9. Tax or VAT information
   Applicable tax rates, tax amounts and registration details.
10. Total amount
    The total amount before and after tax, as applicable.
11. Payment terms and due date
    The agreed period for payment and the calculated payment date.
12. Payment information
    Approved bank or payment details according to company requirements.

A purchase-order number may be an important company requirement even when it is not a general statutory requirement. Suppliers should therefore receive clear invoicing instructions before the first invoice is submitted.

Invoice matching

Invoice matching is the process of comparing a supplier invoice with purchasing and delivery information.

The objective is to confirm that the company is being invoiced for the correct goods or services, at the correct price, and in the correct quantity.

Two-way matching

Two-way matching compares:

• the purchase order; and
• the supplier invoice.

The system or Accounts Payable checks whether details such as price, quantity, currency and supplier information are consistent.

Two-way matching may be used when a separate delivery confirmation is not required or when the company’s process allows it.

Three-way matching

Three-way matching compares:

1. the purchase order;
2. the goods receipt or service acceptance; and
3. the supplier invoice.

The purchase order shows what was ordered and under which commercial conditions.

The goods receipt or service acceptance confirms what was delivered and accepted.

The invoice shows what the supplier is requesting payment for.

When all three records match within permitted tolerances, the invoice can usually continue through the process. When they do not match, the invoice may be blocked for investigation.

Common reasons why an invoice is blocked

An invoice may be blocked because of:

• an incorrect or missing purchase-order number;
• an invoice price that differs from the purchase-order price;
• an invoiced quantity that exceeds the received quantity;
• a missing goods receipt;
• a service that has not been accepted;
• a partial delivery;
• an unapproved freight or handling charge;
• an incorrect currency;
• incorrect tax information;
• a duplicate invoice;
• incorrect supplier information;
• an invoice sent to the wrong legal entity;
• payment terms that differ from the agreement.

An invoice block is not necessarily evidence that the supplier has done something wrong. The problem may also originate in the purchase order, delivery registration or internal process.

The purpose of the investigation is to establish what happened and correct the appropriate record.

Electronic approval of supplier invoices

Many organizations use an electronic workflow to review and approve supplier invoices before payment.

The invoice may arrive as an electronic invoice, through a supplier portal, by email or as a scanned document. An invoice-management system extracts the information and connects the invoice to the relevant supplier, purchase order, receipt and accounting data.

The purpose of invoice approval is not simply to confirm that an invoice has arrived. The approver confirms that the company should pay the invoice.

Automatic approval of matched invoices

When the invoice matches the purchase order and goods receipt or service acceptance, the system may approve it automatically.

This is sometimes called touchless invoice processing because no person needs to manually review every correctly matched invoice.

Automatic approval can reduce administrative work, but it depends on accurate information earlier in the process. The purchase order must be correct, the delivery must be registered and the supplier must follow the invoicing instructions.

Manual approval and exception handling

When information does not match, the system may send the invoice to a buyer, requisitioner, budget owner or manager.

The person receiving the invoice may need to:

• approve an acceptable difference;
• correct the purchase order;
• register a missing goods receipt;
• confirm that a service has been completed;
• explain an agreed price change;
• request a corrected invoice;
• request a credit invoice;
• reject the invoice;
• send the invoice to another responsible person.

The buyer should only approve differences that can be supported by an agreement or documented business event.

An invoice should not be approved only because the supplier is asking for payment or because the due date is approaching.

PO invoices and non-PO invoices

A PO invoice refers to an approved purchase order. It can normally be checked against the quantities, prices and terms already recorded in the purchasing system.

A non-PO invoice does not have the same purchasing reference. It may therefore require manual coding and approval by the responsible budget owner.

Examples of non-PO invoices may include certain taxes, fees, utilities or other purchases that the company has decided to manage outside the normal purchase-order process.

Buyers should encourage the use of purchase orders whenever the company’s procurement process requires them. An accurate purchase order supports automated matching and reduces manual invoice administration.

Why timely approval matters

A correct invoice can still be paid late if it remains in an approval queue.

Delayed approval can lead to:

• supplier questions and reminders;
• late-payment charges;
• missed early-payment discounts;
• inaccurate cash-flow forecasts;
• increased administrative work;
• damaged supplier relationships;
• interruption of deliveries or services.

Buyers should therefore monitor invoice exceptions assigned to them and respond promptly.

When an invoice cannot be approved, the reason should be documented and communicated to Accounts Payable and, when appropriate, to the supplier.

Electronic approval and internal control

An electronic approval system creates an audit trail showing:

• who reviewed the invoice;
• when it was reviewed;
• what decision was made;
• which changes were made;
• why an exception was approved or rejected.

The system may also apply approval limits. For example, a manager may be authorized to approve invoices up to a certain value, while higher-value invoices require additional approval.

A good process also separates important responsibilities. The person creating or changing a supplier, ordering goods, approving an invoice and executing the payment should not have uncontrolled authority over the entire transaction.

Electronic approval supports control, but technology cannot replace accurate information and responsible decisions.

Practical example: An invoice quantity does not match

A buyer orders 100 units at EUR 20 per unit.

The supplier delivers 90 units, and the warehouse registers receipt of 90 units. The remaining ten units are shown as a backorder.

The supplier then issues an invoice for all 100 units.

The invoice-management system compares:

• purchase order: 100 units;
• goods receipt: 90 units;
• supplier invoice: 100 units.

Because the received and invoiced quantities do not match, the invoice is blocked and routed for review.

The buyer should investigate:

• Are the remaining ten units still to be delivered?
• Did the supplier issue the invoice too early?
• Does company policy allow partial payment?
• Should the supplier issue a corrected invoice?
• Is the goods receipt incorrect?
• Was there another documented agreement?

The buyer should not simply approve the full invoice to remove it from the queue.

The correct response may be to pay only for the 90 received units, wait for the remaining delivery, correct an incorrect receipt or request a revised invoice. The appropriate action depends on the agreement and company policy.

Payment terms are commercial terms

Payment terms define when and under which conditions the supplier will be paid.

Examples include:

• payment within 30 days;
• payment within 60 days;
• payment in advance;
• payment upon delivery;
• milestone payments;
• payment after acceptance;
• partial payment;
• early-payment discount.

Payment terms influence:

• company cash flow;
• working capital;
• supplier cash flow;
• supplier pricing;
• commercial risk;
• invoice due dates;
• supplier relationships.

Buyers should not treat payment terms as an administrative detail. Payment terms are part of the commercial agreement and should be recorded correctly in the purchase order and supplier data.

The payment term on the supplier invoice should normally correspond with the agreed term. A supplier should not change the agreed payment term simply by entering a different term on the invoice.

Why timely supplier payment matters

Suppliers expect to be paid according to the agreement.

Repeated late payments can:

• reduce supplier trust;
• create additional administrative work;
• result in payment reminders or penalties;
• make suppliers less willing to prioritize the customer;
• affect future negotiations;
• increase the risk of delivery interruptions;
• create financial pressure for smaller suppliers.

The buyer may not control the final payment execution, but the buyer can prevent many delays by:

• creating accurate purchase orders;
• registering or supporting timely receipt confirmation;
• resolving invoice exceptions;
• documenting agreed changes;
• responding to Accounts Payable;
• communicating clearly with the supplier.

Good supplier relationships depend not only on how the purchase is negotiated, but also on whether the buying company fulfils its payment obligations.

Reconciliation and supplier statements

Accounts Payable may reconcile supplier accounts by comparing invoices, credit invoices and payments with the company’s accounting records.

A supplier may also send a statement showing unpaid or overdue invoices.

The buyer does not normally perform the financial reconciliation. However, procurement may need to help when a difference relates to:

• an invoice dispute;
• returned goods;
• a missing credit invoice;
• an incorrect purchase order;
• a disputed price;
• an unresolved delivery;
• a cancelled order;
• an unrecorded commercial agreement.

The buyer should provide clear documentation and avoid making accounting decisions outside the buyer’s authority.

Invoice automation

Invoice automation can make the Accounts Payable process faster and more controlled.

Common functions include:

• electronic invoice capture;
• data extraction;
• duplicate-invoice detection;
• purchase-order matching;
• tolerance checks;
• approval routing;
• reminders and escalation;
• exception management;
• audit trails;
• payment scheduling;
• accounting and ERP integration;
• reporting and analysis.

Automation reduces manual work when purchasing information is accurate. It does not compensate for unclear agreements, incorrect purchase orders or missing delivery records.

The best way to improve invoice automation is often to improve the quality of the information created before the invoice arrives.

Publish clear invoicing instructions for suppliers

Companies should make their invoicing requirements easy for suppliers to find.

This information can be published in a supplier portal, supplier handbook, onboarding package or Accounts Payable section of the company website.

Instructions may include:

• correct legal entity and invoicing address;
• accepted invoice formats;
• electronic invoicing details;
• supplier portal instructions;
• required purchase-order reference;
• rules for one or several purchase orders per invoice;
• required invoice content;
• tax requirements;
• contact details for invoice questions;
• procedure for credit invoices;
• information about rejected invoices;
• rules for changing bank details.

Clear instructions improve invoice quality and reduce disputes.

Bank-detail changes should follow a controlled verification process. Buyers and Accounts Payable should not change supplier payment details based only on an unverified email.

What should a buyer do when an invoice is incorrect?

When an invoice is incorrect or blocked, the buyer should:

1. Review the purchase order and relevant contract.
2. Check the delivery or service-acceptance record.
3. Identify the exact difference.
4. Confirm whether the internal records are correct.
5. Contact the supplier when clarification is required.
6. Request a corrected invoice or credit invoice when appropriate.
7. Correct the purchase order only when the commercial agreement supports the change.
8. Document the reason for the decision.
9. Inform Accounts Payable about the agreed resolution.
10. Follow up until the issue is closed.

The objective is not simply to release the invoice. The objective is to ensure that the financial transaction reflects what was ordered, delivered, accepted and agreed.

Common mistakes buyers should avoid

Approving without checking

Approving an invoice without verifying the price, quantity or delivery can result in an incorrect payment.

Correcting the purchase order to match the invoice

A purchase order should not be changed only to make an invoice pass the matching process. Any change must reflect a genuine and approved commercial agreement.

Forgetting the goods receipt

A supplier may have delivered correctly, but the invoice may remain blocked because the receipt has not been registered.

Accepting unapproved additional charges

Freight, handling, administration and other charges should be checked against the purchase order or contract.

Ignoring an approval queue

A delayed response can cause late payment even when the invoice itself is correct.

Assuming Accounts Payable knows the commercial agreement

Accounts Payable can compare documents, but it may not know what the buyer and supplier discussed. Important changes must be documented in the purchasing system or contract records.

Treating payment terms as an invoice decision

Payment terms should be agreed during sourcing, contracting or ordering. They should not be determined by whichever term the supplier prints on the invoice.

Failing to follow up a credit invoice

When goods are returned or a price is corrected, the buyer should ensure that the related credit invoice is received and processed.

How this connects to procurement roles

Operative procurement

This topic primarily belongs to operative procurement.

Operative buyers work closely with purchase orders, supplier confirmations, deliveries, invoice differences, returns and supplier communication.

They need to understand how their daily actions affect invoice matching and payment.

Tactical procurement

Tactical buyers define payment terms, pricing structures, invoicing requirements and commercial conditions in RFQs, negotiations and contracts.

Clear commercial terms reduce invoice disputes during the operative phase.

Procurement management

Procurement management should ensure that procurement and Finance work together effectively.

This includes:

• approval rules;
• purchase-order compliance;
• delegation of authority;
• supplier master-data controls;
• payment-term policies;
• invoice-dispute procedures;
• process ownership;
• performance indicators;
• improvement of procure-to-pay processes.

Buyer checklist

Before the supplier invoices:

• Is the purchase order correct and approved?
• Does the supplier have the correct purchase-order number?
• Are price, quantity and currency correct?
• Are payment terms recorded?
• Are delivery and freight conditions clear?
• Has the supplier received the invoicing instructions?

After delivery:

• Has the goods receipt or service acceptance been registered?
• Are quantity or quality differences documented?
• Have returns been recorded?
• Has the supplier been informed about any dispute?

When an invoice is blocked:

• What information does not match?
• Is the purchase order correct?
• Is the receipt correct?
• Is the invoice correct?
• Is there documented support for approving the difference?
• Is a corrected invoice or credit invoice required?
• Has Accounts Payable received the necessary explanation?

Related learning

Buyers who want a broader understanding of daily purchasing responsibilities can continue with the Learn How to Source course Basics for an Operative Buyer.

The course provides a structured introduction to the operative procurement role and the processes that buyers work with in their daily activities.

You may also read:

• Financial Transactions in Procurement: How Buyers Avoid Payment and Invoice Problems
• How Purchase Orders Support Procurement Control

Frequently asked questions

What is Accounts Payable?

Accounts Payable is the function responsible for receiving, checking, recording and processing supplier invoices and preparing approved invoices for payment.

Is the buyer responsible for paying supplier invoices?

Normally, no. Accounts Payable or Finance executes the payment. The buyer supports the process by creating accurate purchasing documents, confirming delivery information and resolving commercial differences.

What is three-way matching?

Three-way matching compares the purchase order, goods receipt or service acceptance, and supplier invoice. The invoice can normally proceed when the information matches within permitted tolerances.

Why is my supplier’s invoice blocked?

Common causes include an incorrect price, quantity difference, missing goods receipt, incorrect purchase-order number, unapproved additional charge, tax issue or duplicate invoice.

What does an invoice approver confirm?

The approver confirms that the goods or services were ordered, delivered or accepted, correctly priced and eligible for payment.

Can an invoice be approved automatically?

Yes. When the invoice, purchase order and receipt match according to the company’s rules, the system may approve the invoice automatically.

What is a non-PO invoice?

A non-PO invoice is an invoice that is not connected to a purchase order. It usually requires more manual coding, review and approval.

Should a buyer change a purchase order to match an invoice?

Only when the purchase order is incorrect and the change reflects an approved commercial agreement. A purchase order should not be changed merely to release an invoice for payment.

Who should resolve an invoice price difference?

Accounts Payable identifies or routes the difference, but procurement may need to confirm the agreed price and resolve the issue with the supplier.

Why do suppliers need clear invoice instructions?

Clear instructions help suppliers submit invoices with the correct company information, purchase-order reference, format and tax details. This reduces rejections, manual work and payment delays.

Conclusion

Accounts Payable and procurement have different responsibilities, but they depend on each other.

Accounts Payable manages invoice processing and payment administration. Procurement creates many of the commercial documents and operational records that make correct payment possible.

For a buyer, the most important lessons are:

• create accurate purchase orders;
• make payment terms clear;
• ensure deliveries and services are registered;
• understand two-way and three-way matching;
• handle electronic invoice approvals responsibly;
• resolve differences promptly;
• document commercial changes;
• follow up credit invoices and returns;
• communicate with Accounts Payable and suppliers.

A purchase is not fully completed when the goods arrive. It is completed when the physical, commercial and financial records are aligned.