How to Invoice a Government Customer
Government bodies pay reliably, but only when the paperwork matches their process to the letter. Get the purchase order, contact and references exactly right, and payment runs smoothly.
In this answer
- Match the invoice to the agency's purchase order and process
- Include every reference their accounts system requires
- Send the invoice to the correct contact or portal
- Meet their terms and formatting expectations
- Keep records tidy for compliance and audit
6 min
The purchase order is non-negotiable
Government and council customers almost always raise a purchase order (PO) before work begins, and they generally will not pay an invoice that does not quote it. The PO number is the single most important reference on the invoice — get it wrong or leave it off and the invoice can be rejected outright, no matter how good the work was.
If you were asked to start before a PO existed, chase the number before you invoice. Quoting it prominently — often near the top of the invoice — lets their accounts payable team match your invoice to the commitment already in their system, which is what unlocks payment.
Include every reference they ask for
Agencies often require specific references beyond the PO. Check what they specified at engagement and include all of it.
- Purchase order number
- Contract or agreement number, if any
- The cost centre or department reference
- The named contact or requisitioner
Missing a required reference is one of the most common reasons a government invoice sits unpaid. When in doubt, ask their contact exactly what the invoice must quote — it is a normal question and they will have a standard answer.
Send it the way they want it sent
Many government bodies have a defined channel for invoices: a dedicated accounts payable email, an online supplier portal, or even electronic invoicing standards. Sending your invoice to your day-to-day project contact instead of the proper channel is a frequent cause of delay, because it never reaches the people who pay it.
Confirm the submission method upfront. If they use a portal, register early so you are not scrambling at invoice time. Following their process precisely is the single biggest lever you have on getting paid on schedule by a public-sector customer.
What to include for a government invoice
Your government-customer checklist:
- 'Tax Invoice' (GST if registered) and a unique number, plus your ABN
- The agency's correct legal name and address
- Purchase order number, prominently shown
- Any contract, cost-centre or department references required
- Clear line items matching what the PO authorised
- Subtotal, GST and total due
- Payment details and their stated terms
- Submission to the correct AP contact or portal
Keep clean copies for audit. Build a compliant layout with the free Invoice Generator and reuse it across public-sector work.
Key takeaways
- Always quote the purchase order number — no PO often means no payment
- Include every reference the agency requires, not just the PO
- Submit through their proper channel, portal or AP email
- Match your line items to what the PO authorised
- Keep tidy records for audit and compliance
Frequently asked questions
What if I don't have a purchase order number?
Get one before invoicing. Most government bodies will not pay an invoice without a matching PO, even for work already done. Contact your requisitioner and ask them to raise or supply the PO.
Why was my government invoice rejected?
The most common reasons are a missing or incorrect PO number, a required reference left off, line items that do not match the PO, or sending it to the wrong place. Check each against what they specified.
Do government customers pay faster or slower?
They are generally reliable payers once an invoice is correctly submitted, but their process is strict. Getting the references and channel right the first time is what keeps payment on schedule.
Build a compliant invoice in minutes
Use the free Invoice Generator, then let Merion recover anything that goes unpaid — commission-only.