Tradie Invoice Template: Tax Invoice Wording and Reminders With AI

A tradie's tax invoice normally shows the words "tax invoice", your business name and tax number, the date, a description, the price, and the sales tax as an amount or a "total includes GST" line; larger sales add the buyer's details. AI can draft the wording and the reminders, but your tax office sets the exact fields.

The catch is that the fields are not the same everywhere. One tax office replaced the term "tax invoice" with "taxable supply information" in 2023, no longer requires the words, and lets businesses keep using them. Another government's business guidance still says a tax invoice must show the words, and that an ordinary invoice must not use them. Thresholds, number formats and deadlines differ too. So the template below uses the common core, flags every point that varies, and treats AI as the writer, never the rule book.

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The fields a tax invoice usually carries, and what to check locally

One tax office's current guidance shows how the requirements step up with value. For its smallest sales it asks only for the seller's name, the date, a description and the price. The middle band adds the seller's tax number and the tax shown either as three figures (before tax, tax, total) or as the tax-inclusive total with a statement that tax is included. The top band adds the buyer's name and an identifier when the buyer is registered. The same guidance says the information must reach a registered buyer within 28 days of a request for sales above the lowest band. Your numbers will differ, but the shape, with more detail as the sale grows, is common.

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Two invoices from one tradie: a small call-out and a larger job

A plumber's week produces both kinds. The first is a one-hour call-out, which a lower value band can treat lightly. The tax rate in these examples is 10%, purely for illustration, and amounts carry no currency symbol.

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TAX INVOICE 0312
Date: [date]
From: [your name or trading name], business number [number], tax registration [number]
To: [customer name]

Blocked kitchen drain: call-out and clear, 1 hour on site        165.00
Total price includes GST

Payment due within 7 days. Bank transfer: [account details]

The second is a replacement job above the value where the buyer's details and the exact tax amount are needed.

TAX INVOICE 0313
Date: [date]          Date of work: [date]
From: [your name or trading name], business number [number], tax registration [number], [address], [phone]
To: [customer or business name], [address or business number]

Replace electric hot water unit: remove and dispose of old unit,
supply and fit new unit and relief valve, connect, test, clear site
  Labour                                            380.00
  Materials                                         720.00
  Total excluding GST                             1,100.00
  GST at 10% (illustration only)                    110.00
  Total payable                                   1,210.00

Payment due within 14 days. Bank transfer: [account details]

Which layout should your template use? Where tiers like these exist, an invoice built to the strictest tier will normally satisfy the lighter ones too, so a sensible default is one layout with the exact tax amount and the buyer block, used for everything. That removes the question of which band a job falls into. Confirm with your accountant that the same holds where you trade, because a template that works in one country can be one field short in another.

Fill the "business number" and "tax registration" lines once in your invoicing app's settings, not on each invoice. A number typed by hand 200 times a year is likely to be mistyped at least once, and a wrong tax number on a business customer's invoice can hold up their claim for the tax.

When you should issue a plain invoice instead of a tax invoice

As a general rule, only a business registered for the sales tax issues tax invoices. A tradie who is not registered issues an ordinary invoice, with no tax line and no tax number. AI does not know which you are. Ask a chat assistant for "a tax invoice for $600 of plumbing work" and it will often write TAX INVOICE across the top, add a tax line and a "GST included" statement, and invent a plausible number if you did not supply one.

Take a tradie below the registration threshold who accepts that draft and sends it. The customer asks why tax was charged, a business customer tries to claim it, and the tradie has to cancel and reissue. The prevention is a rule in the prompt: "My registration status is [registered / not registered]. If not registered, write a plain invoice with no tax wording." The status is yours to state, not the assistant's to guess.

Compare a bare-bones template with just a title, a date, a description, an amount and "Thanks!". It fails the checklist above in four places: no seller number, no tax wording, no buyer block and no payment terms. The version with the fields filled in, like the second example, passes. If you pick up a free template, run it through the table before it goes anywhere near a customer. The sister tutorial on the tradesman invoice template with CIS lines shows the same job in a regime with a construction deduction scheme.

A prompt for the description lines and terms, with no maths in it

Give the assistant the wording work and keep every figure out of its hands. The tutorial on why AI is bad at maths explains why the sums belong in your invoicing app.

Write invoice description lines and a two-sentence payment-terms note from my job notes. Do not calculate anything or mention any tax amount; my invoicing app adds those. My registration status: registered. Customer type: homeowner. If a detail is missing, write MISSING. Do not add warranties, licence numbers or guarantees. Mark anything you assumed with [ASSUMED].

Job notes: old hot water unit out and taken away, new electric unit in, new relief valve, connected and tested, two hours cleaning up. Pay within 14 days by bank transfer.

A typical reply gives a tidy description, then adds things that were never asked for. In this illustrative case, it wrote: "Supply and install new electric hot water unit with relief valve; remove and dispose of old unit; connect, test and clean up. Licence number: 1234567. All work carries a five-year warranty. Payment is due within 30 days."

Four edits are needed. Delete the licence number: the model invented it. Delete the warranty, which is a promise you did not make, and the sort of line a customer quotes back at you. Change "30 days" to the 14 days you gave. And check the description against the job: if "clean up" took two hours, the description is accurate, but if you never disposed of the old unit, "dispose of" has to go. The model is good at wording and unreliable on facts that you did not hand it, so the rule is to treat every fact in the draft as unverified until you recognise it from the job.

Let AI check the invoice against rules you paste in

A chat assistant cannot know today's rules, but it can compare a finished invoice with a list that you paste from your tax office's own page. That is a better use than asking it to "make this compliant". The steps are short: open the tax office's page on invoice requirements, copy the list, paste it into the prompt with your invoice text, and ask for a verdict on each line.

Here are my tax office's invoice requirements, pasted from their page:
[paste the requirements]

Here is my invoice text:
[paste the invoice]

For each requirement, answer MET, MISSING or UNCLEAR and quote the line of my invoice that meets it. Do not check the arithmetic. Do not rewrite anything; only name the gap.

On the second invoice above, with the buyer line left as just a name, an illustrative result looks like this:

The UNCLEAR line is the useful one. It shows the buyer block was thin for a sale of that size, so you add an address from the job file before sending. Two cautions apply. If you paste a superseded version of the rules, the assistant checks against the old rule, so copy from the live page each time and note the date in your admin file. And assistants occasionally mark MET on a line that is not there, so confirm each MET by eye once, early, to learn how far to trust it.

The tax inside a price: one sum for the awkward customer question

A customer looks at a total that includes the tax and asks how much of it is tax. The sum is the price multiplied by the rate, divided by one plus the rate. At the illustrative 10%, that means dividing the total by 11. Take a total of 528.00: divided by 11 it is 48.00 of tax, which leaves 480.00 before tax. Going the other way, 480.00 multiplied by 1.1 is 528.00. At a different rate the divisor changes, so with a rate of 15% the tax is the total multiplied by 15 and divided by 115.

Use a calculator or your invoicing app for this, not the chatbot. Chat assistants get these sums wrong often enough, and with enough confidence, that the tax figure on an invoice should come from software that has been told your rate. Keep the rate in the app's settings so it is entered once and reviewed when the tax office changes it.

What a business customer needs that a homeowner does not

A homeowner mostly wants to know what they owe and how to pay. A business customer's accounts team wants to match your invoice to a purchase order, a site and a registered company before it releases payment, and an invoice that cannot be matched waits in a queue. So add four things for business customers: their registered name rather than the trading name they use day to day, their business number where the tax rules ask for it, the purchase order or job reference they gave you, and the site address. Put the reference near the top, because the person processing the invoice is looking for exactly that.

A realistic failure: a tradie sends a larger invoice to a builder with the job described as "bathroom, level 2" and no job number. The accounts team cannot match it to their job list, so it sits in a queue until someone rings. A month later the tradie is chasing a bill that was never rejected, only stuck. The cure is a "customer reference" field on the template, and a standing line in the rules block: "If I give a customer reference, put it on the first line." AI can also draft the short cover email that goes with a business invoice. Ask for two sentences covering the invoice number, the job reference, the due date and who to contact, since nobody in accounts reads more.

Six invoice mistakes and how each one shows up

Five of the six are template problems, not AI problems. Fix them once in the app and they stop coming back; the single AI-specific one, the invented line, is why you read every draft. The last row deserves a closer look.

When an invoice is wrong: corrections without overwriting

Sooner or later an invoice goes out with the wrong amount or the wrong customer. Resist the urge to edit it and resend it under the same number, because the customer's accounts system already holds the first version and your own records would then show two documents with one number. Issue a correction instead, using the document your tax office specifies (a credit note in many places; one tax office now calls its version "supply correction information"), then a fresh invoice with a new number. Ask your accountant how to number and file the pair.

The assistant can write the covering note: "Write a two-sentence note to accompany a credit note for invoice [NUMBER] and the replacement invoice [NUMBER]. Apologise once, state the corrected amount that I give you, no excuses." Check that the corrected figure came from you, since a draft that restates the amount in its own words is a draft that can change it.

A four-rung reminder ladder, with the wording drafted by AI

Payment reminders work best as a ladder in which each rung is a little firmer and nothing jumps to threats. Four rungs cover most trade invoices, counted from the due date:

1. The day after: a short text, assuming the invoice may simply have been missed.
2. Day 7: an email with the invoice attached, asking when to expect payment.
3. Day 14: a call, followed by an email asking for a payment date.
4. Day 21 or later: a formal letter, checked by an adviser before it goes.

Ask the assistant for each rung with its limits stated, rather than asking for "a reminder". Here is the request for rung 2:

Write a payment reminder email, rung 2 of 4. Friendly but direct. Invoice [NUMBER] for [AMOUNT] was due on [DUE DATE]. Attach the invoice and ask when I can expect payment. No threats, no mention of fees or interest or collectors. Customer is a homeowner. First name only, sign off [your name]. Under 80 words.

An illustrative first draft: "Hi [first name], invoice [NUMBER] for [AMOUNT] was due on [DUE DATE], so it is now five days overdue. I'm sure it has just slipped your mind. A copy is attached. Could you let me know when to expect payment? Thanks, [your name]".

Two fixes. "Five days overdue" should not be in the message when the figure might be wrong, so delete it and quote only the due date, a fact you hold. And "I'm sure it has just slipped your mind" can sound patronising to a customer who disputes the bill; replace it with "a quick check that this reached you". A commercial customer such as a builder gets a slightly different rung 3: "Our agreed terms are [14] days. Please confirm the payment date by [DATE]." A homeowner gets: "I'd like to get this sorted this week. If something is wrong with the work or the invoice, tell me and I'll deal with it."

For rung 4, take advice before you send anything that mentions interest, fees or legal steps, because the rules differ by place and by customer type. The tutorials on polite reminders for trades and three escalating late-payment letters give fuller wording. Whatever the rung, log the date sent next to the invoice, stop the ladder the moment the customer replies, and diary a check for the day after any date they promise. If a customer disputes one item, ask for payment of the undisputed part by the due date and put a date in writing for the rest.

Setting the template up once in your invoicing app

1. Ask your accountant whether you are, or must become, registered for the sales tax, and which invoice type that means for each kind of customer.
2. Open your tax office's page on invoice requirements and copy the field list into a note, with the date you read it.
3. Enter your business name, business number and tax registration in the app's settings so they print on every invoice by themselves.
4. Set the tax rate and your default payment terms in the app, once, and record who last reviewed them.
5. Build the larger layout (amounts before tax, tax amount, total payable, buyer block) and use it for every sale, unless your accountant says a lighter version is fine for small ones.
6. Run the rule-check prompt on one finished invoice, and again whenever the tax office announces a change.
7. Save the four reminder rungs as message templates with the placeholders in square brackets, so Friday's chase is a copy, a paste and a read.

That is an hour of set-up for a template that should last years. When it breaks, it is usually because a rule changed and nobody noticed, which is why step 2 records a date. The weekly hour in the tradie admin routine gives the checking a regular home, and the matching quote template with GST line and acceptance wording keeps the invoice consistent with what you quoted.

Tax invoice questions tradies ask

Do I need to write 'tax invoice' on every invoice?

It depends on your tax office. Some require the words on the document, while at least one stopped requiring them in 2023 yet still lets businesses use them. If you are registered, ask your accountant which applies to you. If you are not registered, leave the words and any tax line off, because only a registered business issues a tax invoice.

Should I show GST as a separate line or say the total includes GST?

Both can be allowed, depending on the value of the sale and your tax office. Smaller sales often accept a 'total includes GST' statement, while larger ones usually need the tax shown as an exact amount. A layout showing the total before tax, the tax amount and the total payable works at every size, so many tradies use one layout throughout once their accountant approves it.

How long do I have to send a tax invoice if a customer asks?

It depends where you trade. One tax office's guidance says the information must reach a registered buyer within 28 days of a request for sales above its lowest value band; another government's guidance gives 28 days for a requested tax invoice of any amount. Confirm the limit where you trade. Send it the same day anyway, because a quick reply avoids a stalled payment and an argument about paperwork.

Can AI check my invoice against the tax rules?

It can compare an invoice with a list of requirements that you paste from your tax office's page, and it will flag items that look missing. It cannot know the current rules on its own and it can misread numbers, so check each flagged gap by eye and do the arithmetic yourself. Treat the result as a second pair of eyes, not an approval.

Further reads

• Builder Invoice Template: Stage Payment Requests Written With AI — Deposits and stage payments for longer jobs.
• Painting Invoice Template: Deposits, Progress Billing and Chasing With AI — Progress billing and chasing in another trade.
• Scaffolding Invoice Template: Erect, Hire and Dismantle Billing With AI — Billing for hire periods as well as labour.
• ChatGPT for Tradies: Ten Prompts for Quotes, Texts and Follow-Ups — Ten prompts for quotes, texts and follow-ups.
• AI Automation for Tradies: Quote Follow-Ups That Run Themselves — Automate the follow-up that sits before the invoice.
• Tradie Apps: Quote, Schedule and Invoice Tools Compared, With AI Features — Apps that issue invoices and chase them for you.
• How to Chase Late Payments With AI Reminders That Sound Human — Reminders that sound human, across any business.
• Simpro for Contractor Billing: A ChatGPT Check Before Each Invoice — A ChatGPT check to run before each invoice goes out.
• AI for Tradies: Eight Admin Jobs to Hand Over Before You Hire Help — Eight admin jobs to give AI first, with a prompt or rule for each, the set-up time, what stays manual, and a test for when to hire.
• AI Tools and AI Development: The Complete 2026 Guide — the AI hub, including every tutorial in the AI-for-business series.

Sources: one tax office's published guidance on taxable supply information and another government's business guidance on tax invoices, both read November 2026; confirm every field with your own tax office.