B2B Invoice Requirements

Purchase orders

Many companies require a valid PO number on every invoice. Ask the buyer's AP contact before the first bill and store the PO on the invoice and in your records.

• Buyer company legal name
• Billing address
• AP email or portal

Billing entity details

Use the legal company name, billing address, and accounts payable email — not only your project contact. Invoices sent to the wrong mailbox often sit unpaid without notice.

• PO number on header
• Department or cost center
• Approver name when required

Tax and registration IDs

Depending on region, buyers may need your tax ID, VAT number, or business registration on the invoice. Requirements vary — this is not tax or legal advice.

• VAT/GST/EIN when applicable
• Not legal advice
• Verify with client AP checklist

Complete vendor onboarding before the first deadline

Large buyers may require a supplier form, bank verification, tax documentation, insurance evidence, portal registration, or an approved purchase order before they can release payment.

Ask the project owner to introduce you to accounts payable before the first invoice. Confirm the legal entity you are billing, submission channel, accepted file format, currency, PO rules, payment term, and support contact.

Finishing these steps early prevents a perfectly written invoice from waiting in an unmonitored mailbox or failing an automated portal check.

Match the invoice to the purchase order

Use the exact supplier name, buyer entity, PO number, currency, and line descriptions the approved order expects.

If the PO contains multiple lines, identify which line each charge uses and do not exceed the authorized quantity or amount without a documented change. Include service dates or delivery references when requested.

Before sending a first invoice, compare it with the buyer's sample or portal checklist. “Common invoice fields” are only a baseline; the customer's workflow and applicable local requirements determine what is actually needed.