What is a purchase requisition in simple terms?

A purchase requisition is an internal permission slip -- an employee asks their company's purchasing or finance department to approve buying something from an outside vendor. Once approved, the company issues a purchase order to the vendor.

Why does my corporate client need a purchase order to pay my invoice?

Large companies use purchase orders as internal controls to ensure all spending is pre-approved and budgeted. If you invoice without a matching PO, the AP department cannot verify the purchase was authorized and will hold your payment until the PO is issued.

How do I get a purchase order from a client?

Ask your client contact to initiate the purchase requisition process as early as possible -- ideally before work begins. Once the requisition is approved internally, the purchasing department issues a PO and shares the PO number with you to reference on invoices.

Does a purchase requisition protect me as a vendor?

Indirectly -- it confirms that the client's organization has authorized the purchase. However, the purchase order is the document you can rely on as a vendor; the requisition is internal paperwork you may never see.

What should I do if a client's invoice is stuck due to a missing PO?

Contact your client's purchasing or AP department directly and ask what PO number to reference. You may also need to work with your client contact to initiate a retroactive requisition. In the future, always confirm the PO number before sending an invoice.

Business

What is Purchase Requisition?

A purchase requisition is an internal approval document that starts the purchasing process inside a company before a purchase order or payment is issued.

A purchase requisition is an internal document used within a company to formally request the purchase of goods or services. It is the starting point of a procurement process: an employee or department identifies a need, fills out a requisition form specifying what is needed, the quantity, the estimated cost, and the business reason, and submits it for internal approval. Once approved, the requisition authorizes the procurement or purchasing department to issue a purchase order to an external vendor. For freelancers working with corporate clients, understanding the purchase requisition process explains why clients sometimes cannot pay an invoice quickly -- the purchase was not pre-approved through a requisition, and the accounts payable department is waiting for the requisition to clear before processing payment.

A purchase requisition works as an internal control mechanism. Before a company commits to spending money with a vendor, it routes the request through an internal approval chain -- a manager, a department head, or a finance officer, depending on the amount and the company's policies. This approval process ensures that expenditures align with the budget and that multiple people authorize significant purchases before funds are committed. Once the requisition is approved, the purchasing department converts it into a purchase order, which is sent to the vendor. The vendor delivers the goods or services and sends an invoice. The accounts payable department matches the invoice to the purchase order and the original requisition before paying -- a process called three-way matching. Without a requisition, the invoice may be held until the approval is obtained.

For freelancers and small business owners, the purchase requisition process affects how and when you get paid by larger clients. If a client's accounts payable department requires a purchase order to process your invoice -- which is common in mid-size and enterprise companies -- ask your client contact to confirm that a PO has been issued before you begin work. Reference the PO number on every invoice you send to that client. Failure to include the PO number is one of the most common reasons invoices get delayed in corporate AP systems. For new client relationships with large companies, ask during the contracting phase: 'Does your company use purchase orders for vendor payments, and if so, can you send me the PO before I invoice?' This simple question prevents weeks of payment delays.

A purchase requisition is an internal document requesting permission to buy -- it has not yet committed the company to any external purchase. A purchase order is the external-facing document sent to the vendor after the requisition is approved -- it represents a formal commitment to buy at the stated price and quantity. Vendors often treat purchase orders as binding contracts. From a freelancer's perspective, the purchase order is what you care about: it confirms the client is authorized to purchase your services, establishes the agreed price, and gives you a PO number to reference on invoices. Purchase requisitions are internal paperwork you may never see; purchase orders are what vendors receive and reference throughout the project.

To process a purchase requisition from a client's perspective: First, when onboarding a new corporate client, ask whether they require a purchase order for vendor payments and what their requisition process entails. Second, request the PO number before beginning work on the project. Third, include the PO number prominently on every invoice you send. Fourth, confirm with your client contact that the requisition has been approved and the PO issued before submitting your invoice. Fifth, if your invoice is delayed, ask the client's AP department whether the PO has been received and whether the invoice matches the PO amount. Sixth, for ongoing retainer relationships, confirm that the PO covers the full retainer period or ask for a new PO for each renewal period.

Eonebill makes it easy to include PO numbers and client-specific billing references on your invoices, reducing the risk of payment delays due to missing information. Our [free invoice generator](/free-tools/invoice-generator) supports custom fields so you can match whatever information your client's AP department requires. Visit [Eonebill pricing](/pricing) to explore how Eonebill supports your corporate client billing.

1. Invoicing a corporate client without a PO number -- many AP departments will not process an invoice without a matching PO, and your payment will be held until one is issued. 2. Assuming approval from one contact means the purchase is authorized -- the person you work with may not have procurement authority; always ask whether a PO is required. 3. Starting work before the requisition is approved -- if the requisition is denied, you may complete work without any authorization or obligation to pay. 4. Using a different amount on your invoice than what was on the PO -- three-way matching requires the invoice to match the PO; discrepancies trigger manual review and delays. 5. Not following up on delayed POs -- if a client promised a PO by a certain date, follow up proactively rather than waiting indefinitely.

Learn more about related topics: [RFP Meaning](/glossary/rfp-meaning), [Bid Bond](/glossary/bid-bond), [Accounts Payable Aging](/glossary/accounts-payable-aging), [Net-30 Payment Terms](/glossary/net-30-payment-terms).