Sign and approve a purchase order online

What a purchase order is, legally

A purchase order (PO) is a buyer's written offer to buy specific goods or services at a stated price. On its own it is only an offer. It becomes a contract when the supplier accepts it, whether by signing an acknowledgement, by confirming in writing, or simply by delivering.

That last route is where trouble starts. If the supplier delivers and sends an invoice printed with its own terms, it may be unclear whose terms apply. A signed acknowledgement that expressly accepts the buyer's terms closes the question.

What every PO should state

Finance teams reconcile POs against invoices and delivery notes, the 'three-way match'. Missing fields break that match.

• PO number, unique and quoted on every invoice.
• Supplier name, address and tax or VAT number.
• Line items: description, part number, quantity, unit price, tax and total.
• Delivery address, delivery date and shipping terms.
• Payment terms, for example 30 days from receipt of a valid invoice.
• A reference to the buyer's terms and conditions, attached or linked.
• Approval: who authorised the spend, and when.

Internal approval, then supplier acceptance

Most companies have spend limits: a manager approves up to one figure, a director above it. A signature on the PO is the record that the right person approved the spend before it was committed.

In Sign PDF, set the order to 'one after another'. The approver signs first; only once they have, the supplier receives the PO to acknowledge. If the approver declines, they can give a reason and the PO never reaches the supplier.

Validity and the battle of the forms

There is no special formality for a purchase order, so an e-signature is valid under the US ESIGN Act, which covers UCC Article 2 sales of goods, and under UK, EU and UAE law. Under UCC section 2-207, an acknowledgement that adds different terms may still form a contract, with the conflicting terms dropping out or being read in depending on the circumstances. English law tends to apply the 'last shot' rule.

Not legal advice. For large or long-running supply relationships, a signed master agreement with POs issued under it is cleaner.

Where Sign PDF fits, and where it does not

Sign PDF is a good fit if you raise POs in a spreadsheet or accounting tool, export them as PDF and want a signed, sealed approval and acknowledgement. It is not a procurement system: it does not create POs, match invoices or sync with your ERP, and it has no API or integrations. If you raise hundreds of POs a week, a procurement platform with built-in approval will suit you better.

How to send a PO

Export the PO to PDF or Excel and upload it. Sign PDF places an approval signature where the PO says 'Authorised by' and an acknowledgement block for the supplier if there is one. If not, type 'add a supplier signature and date at the bottom' and the assistant adds it.

When everyone has signed, the sealed PDF and certificate show who approved it and when the supplier accepted. With the Full plan at $10 a month you can save your PO layout as a template.