Selling Online to Public-Sector Buyers: Purchase Orders, P-Cards and E-Invoicing in 2026

The verdict in three sentences

A public buyer does not pay at checkout: it issues a purchase order with a commitment number, receives an invoice through a government e-invoicing portal (Chorus Pro in France), and the treasury pays by bank transfer within 30 days (50 days for a French public hospital). Your B2B store must therefore offer a pay on invoice checkout next to the government purchasing card (P-card), and produce invoices that are accepted the first time. Budget 6,000 to 18,000 EUR excl. VAT depending on automation, quickly recovered once a few councils or hospitals order online instead of by email.

The three ways a public buyer pays you

A supplier of school supplies, medical consumables or furniture selling to the public sector meets three circuits. The purchase order paid by treasury transfer is the norm: the authorising officer approves the invoice and the public accountant pays. The purchasing card covers small recurring spend: the issuing bank pays you within days and the entity settles later. The call-off order under a framework agreement (or a central purchasing body) follows the purchase order circuit with fixed prices.

In France, late payment triggers statutory interest at the ECB rate plus 8 points and a fixed 40 EUR recovery fee per invoice. The UK Procurement Act 2023, in force since February 2025, imposes 30-day terms down the supply chain, and the US Prompt Payment Act adds interest after 30 days. Few suppliers claim these amounts: your back office can compute and add them automatically.

What to build, and what it costs

A consumer store is not enough. You need customer accounts per entity (one council, several buying departments), a mandatory field for the commitment or PO number, an approval workflow on the buyer side, and a connection to the e-invoicing channel: Chorus Pro API or Factur-X files in France, PEPPOL in the UK NHS, vendor portals and a SAM.gov registration for US federal buyers. With the French B2B e-invoicing reform, mandatory for receipt since September 2026, the same flow also serves your private customers.

The low end is an extension of an existing store (WooCommerce, Shopify Plus, PrestaShop) with semi-automatic portal upload. The high end is a custom platform synced with your ERP that processes the invoice statuses returned by the portal (rejected, approved for payment, paid).

The mistakes that block payment

A rejected public invoice restarts the 30-day clock. The usual causes: wrong entity identifier (SIRET in France), missing service code, missing PO number, amount different from the order. A well-designed site makes these fields mandatory at checkout and copies them onto the invoice: rejection typically drops from 10 to 15 % of manually keyed invoices to under 2 %, an order of magnitude seen on this kind of project.

Mini case study

Claire runs a school supplies SME near Lyon: 180 public customers, 2,400 public invoices a year, average basket 900 EUR excl. VAT. Today 12 % of invoices are rejected and paid on average at 58 days instead of 30. On 2.16 M EUR of public revenue, 28 days of delay mean about 166,000 EUR of extra receivables. With a 14,000 EUR B2B store that enforces the Chorus Pro fields, rejection falls to 2 % and the average delay to 34 days: receivables drop by about 142,000 EUR and the team saves nearly 6 hours of rekeying a week. The project pays for itself in under a year on working-capital financing alone.

FAQ

Can a council pay directly by card on my site?

Yes, if it holds a government purchasing card, often capped between 1,000 and 5,000 EUR per transaction (US P-cards commonly at the 10,000 USD micro-purchase threshold, to be checked against current rules). The issuing bank pays you within 2 to 5 business days.

Is Chorus Pro mandatory for all my French public invoices?

Yes, since 2020 every company must upload invoices addressed to the State, local authorities and public bodies on Chorus Pro. An invoice sent by email or on paper is not accepted.

Can I claim the 40 EUR fee automatically?

The fixed 40 EUR fee and statutory interest are due by law from the first day of delay. Your back office can generate the claim through Chorus Pro without legal action.

Do I need a public contract to sell online to a council?

Below the direct-award threshold (40,000 EUR excl. VAT for supplies in France, order of magnitude to check against the threshold in force), the buyer can order directly. Above it, your online catalogue executes a framework already awarded.

How long until we are live?

Allow 6 to 10 weeks, including 2 to 3 for the portal connection and testing in the qualification environment.

Let's scope your project. We scope your public-sector B2B store, from the pay on invoice checkout to the e-invoicing connection, for an indicative 6,000 to 18,000 EUR excl. VAT delivered in 6 to 10 weeks. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.