How to Write an Invoice as a Tradie in NZ (GST and Non-GST)
- Use a tax invoice with your GST number if registered, or a plain invoice stating no GST if not.
- Write each invoice line exactly as the quote stated it, with added work logged separately and dated.
- Invoicing promptly matters because value scores lowest of all rated dimensions for every trade, down to 95.5 for plumbers.
Most tradies write their first invoice by copying whatever a mate uses, and keep using it for years. The layout survives long after the business has changed: GST registration comes and goes, deposits start being taken, variations start being agreed on site, and the invoice still has one line and a total. Here is how to write one that holds up, in the order you would actually fill it in.
Step one: decide which invoice you are writing
There are two documents, and they are not interchangeable.
If you are GST registered, you write a tax invoice. It carries your GST number and shows GST at 15%, either as a separate line or as a statement that the total includes it.
If you are not registered, you write a plain invoice. It says you are not GST registered and charges no GST. Registration is compulsory once turnover passes $60,000 in 12 months, so if you are anywhere near that number, check with your accountant before the next invoice goes out.
Using the wrong one is not a cosmetic problem. A non-registered business that adds 15% has collected tax it cannot pass on.
Step two: the header
Your trading name, and your GST number if you have one. Your address, phone and email. The invoice number, which should be sequential and never reused. The invoice date. The due date, as a calendar date. The quote or job number the invoice relates to.
For any sale over $1,000, the customer’s name and address or another identifier. Put it on every invoice regardless; it costs nothing and saves a question later.
Step three: the work lines
This is where invoices are won or lost. Write each line the way the quote wrote it. If the quote listed “supply and install 2 x double power points, lounge” then that is the line, with the same price. If something was added on site, it gets its own line, dated, with a note like “agreed with Sarah on site 14 Oct”. If the customer supplied materials, say so, so the labour-only price makes sense.
Avoid single-line invoices for multi-day work. “Electrical work as discussed, $3,450” is an invitation to argue. Nothing was discussed in writing, and the customer’s memory of the discussion is not the same as yours.
Step four: the money
Subtotal excluding GST. GST at 15% on its own line (registered businesses only). Total including GST. Less any deposit received, with the date it was received. Amount due.
The deposit line matters more than it looks. A customer who paid $1,000 up front and receives an invoice for the full amount will ring you. Some will pay it, and then you have a refund to process and a customer who feels overcharged.
Step five: how to pay
Bank account number, account name, and the reference you want them to use (the invoice number is best). If you accept card payment, say how. If you charge interest or an admin fee on overdue accounts, it needs to have been in your terms before the job, not introduced on the invoice.
Step six: send it the same day
The gap between finishing and invoicing is the gap in which the work stops being vivid. Invoice from the van if you can. Across 20,286 publicly posted reviews of NZ electricians, plumbers and painters, value is the lowest-scoring of the four rated dimensions for every trade: 95.5 out of 100 for plumbers, 97.1 for electricians and 97.8 for painters. Customers rate the work highly and the price slightly less so, and the invoice is where they form that second opinion. An invoice that arrives promptly, matches the quote and explains itself gets a better score than the same number arriving three weeks later with no detail.
The gap between finishing and invoicing is the gap in which the work stops being vivid.
Keep a copy
Seven years, for both versions. A folder in your email or a cloud drive is enough. “I cannot find the invoice” is a bad position in a payment dispute and a worse one in an audit.
Use the template
The NZ tax invoice template for tradies in our resource library has both versions side by side, with the taxable supply information rules printed on each page, and an Excel workbook that does the GST, the deposit and the due date for you. Download it, put your details in once, and the structure is handled every time.
The invoice is not paperwork that follows the job. It is the last part of the job, and the part the customer keeps.
What to do on Monday
- Invoice every job the same day you finish it, before details start to fade.
- Check whether you are GST registered and write the correct invoice type, tax or plain.
- List each work item as it appeared in the quote, adding any site variations as separate dated lines.
