How to Write a Tax Invoice That Gets Paid — Australia

The average Australian business invoice takes 27 days to be paid — but a significant proportion of that delay is caused by the invoice itself. A missing purchase order number, an invoice addressed to the wrong entity, or a vague description can send an invoice to the bottom of the queue or into an approval loop that takes weeks to clear. The following principles apply regardless of your industry or invoice size.

1. Use all the mandatory ATO fields

A valid Australian tax invoice must include the following. Missing any of these gives the buyer a legitimate reason to delay payment while they request a corrected version.

The words "tax invoice": Must appear prominently — typically at the top of the document. This is a hard legal requirement under the GST Act.
Your ABN: Mandatory. Without it, payers are required to withhold 47% of the payment. Format it consistently: e.g. ABN 12 345 678 901.
Your business name: Use the registered entity name or the name registered with the ATO — not a trading name unless both are shown.
The date: The date the invoice is issued. Write it in full (e.g. 15 July 2026), not as a number string that can be misread.
A description of each supply: Specific enough to identify the goods or services. "Consulting services" alone is often insufficient — reference the specific deliverable, period or project.
The GST amount or a GST-inclusive statement: Either show GST per line or as a total, or include the statement "Total price includes GST of $X". Our invoice generator handles this automatically.
Total price: The total amount payable. Make this prominent — it is the first thing accounts payable looks for.
Recipient's identity or ABN (invoices $1,000+ inc. GST): For supplies of $1,000 or more (including GST), include the buyer's name and/or ABN. See the full tax invoice requirements guide.

2. Address the invoice correctly

A mis-addressed invoice is one of the most common causes of payment delays. To get this right:

Use the registered entity name — the name that matches the ABN. Verify at the Australian Business Register. Do not use a person's name or a brand name unless it is the registered name.
Send to accounts payable, not the project contact — ask for the accounts payable email address before you do the work. The project manager often has no authority to release payment; accounts payable does.
Include the accounts payable contact name — "Attention: Accounts Payable" or "Attn: Sarah Chen, Accounts" gets the invoice to the right desk faster.
Match the trading entity — if the client operates multiple entities, confirm which entity engaged you. Invoicing the wrong entity (e.g. the holding company instead of the operating company) can result in genuine non-payment.

3. Get the purchase order number right

Many businesses — especially government, large corporates and construction head contractors — operate a three-way matching process: they will not pay an invoice unless it matches a valid purchase order and a goods receipt. If your invoice does not include the PO number, it will not be processed.

Ask for a purchase order number before you start work — not after delivery.
If the client says a PO is coming, wait for it before invoicing.
Reference the PO number prominently on the invoice (e.g. "Your PO: PO-20260614").
If you are told POs are not used, get confirmation in writing — this protects you if the invoice is later queried.

4. Write a specific due date

"Net 30" and "30 days" are ambiguous — does the clock start from invoice date, receipt date, or the end of the month? Write a specific calendar date:

Do: "Due: 29 July 2026"
Avoid: "Net 30", "30 days EOM", "payable within 30 days of receipt"

A specific due date also anchors your reminder sequence — you know exactly when an invoice becomes overdue and when to send the first reminder. Read more in our guide to setting payment terms for B2B.

5. Include your payment details on every invoice

Remove every possible obstacle to payment. Your invoice should include:

Bank name
BSB
Account number
Account name (must match your entity name with the bank)
A specific reference (your invoice number) so the payment can be matched to the invoice

If you accept other payment methods (credit card, PayID, BPAY), include those details too. Reducing friction at the payment stage is one of the highest-impact things you can do to get paid faster.

6. Write a description that passes the "accounts payable test"

The person processing your invoice is often not the person who engaged you. They need to understand what you supplied, without asking. Descriptions that pass the accounts payable test:

"Project management services — Northside Office Fit-Out — May–June 2026" ✓
"Legal services — contract review and advice — Employment Agreement, June 2026" ✓
"Supply and installation — 3× Daikin RAS-M18YAVNA split-system air conditioners — 42 Smith St, Brisbane" ✓

Descriptions that fail:

"Consulting services" ✗
"Labour as discussed" ✗
"Balance of project" ✗

7. Confirm receipt for high-value invoices

For invoices over $5,000, send the invoice by email and then follow up with a phone call or brief email to confirm it has been received by the right person and is in the processing queue. Ask:

"Has the invoice been received and allocated to the correct purchase order?"
"Is there anything else you need from us to process payment?"
"Who is the approval authority for this invoice?"

This one step resolves the vast majority of "we never received it" and "still waiting on approval" delays.

8. Start the reminder sequence immediately when overdue

Do not wait weeks to follow up. Begin the reminder sequence on day one of overdue. Use our payment reminder templates for ready-to-copy email text. Read the full overdue invoice escalation guide for the complete sequence.

Frequently asked questions

Does a tax invoice need to be on letterhead?

No. The ATO does not require any specific format or design. A plain invoice — even handwritten — that contains the mandatory fields is valid. That said, a professional format builds trust and reduces the chance the invoice is questioned or delayed.

What if I forget to include GST on an invoice?

If you are GST-registered and the supply is taxable, you must account for GST regardless of whether you included it on the invoice. You can issue a revised tax invoice or an adjustment note to correct the error. The buyer needs a valid tax invoice to claim their GST credit.

Can I issue a tax invoice before I have done the work?

Yes — a tax invoice can be issued before, during or after delivery. However, the GST liability arises at the earlier of when you receive payment or when you issue the invoice. For deposit invoices, GST is due when the deposit is received.

Does an invoice need a due date?

The ATO does not require a due date on a tax invoice. However, including an explicit due date (e.g. 'Due: 15 July 2026') rather than vague terms (e.g. 'net 30') significantly reduces the likelihood of late payment.

Free tools and related guides

Invoice Generator — ATO-compliant tax invoice, free, no sign-up
Statement Generator — account statements
Australian Tax Invoice Requirements — the full legal detail
Setting Payment Terms for B2B
Payment Reminder Templates
Chasing an Overdue Invoice
Merion Free Tools — late payment cost and ROI calculators
Refer a debt to Merion — commission-only recovery