How to document extra work (and actually charge for it)

Why the verbal agreement fails at invoice time

On site, "yeah, chuck it on the bill" feels like agreement. Six weeks later, on an invoice that's $1,400 bigger than the quote, it isn't. The customer doesn't have to be dishonest to dispute it — they genuinely remember it differently: smaller, cheaper, or "included". You're now negotiating from memory against someone holding your own quote as evidence of what the job was supposed to cost.

The economics are lopsided. Documenting the extra takes a minute or two. Not documenting it costs you the argument, and the usual way out of the argument is knocking money off. Most tradies don't lose extras to customers refusing to pay — they lose them to the quiet discount that ends the awkward phone call.

The minimum viable record

You don't need a formal variation document for every extra (though for contracted building work you may — see below). You need a written record with four elements:

1. What. The extra work, described specifically enough that a stranger could tell it apart from the quoted work. "Replace rotted joist under bathroom floor, approx 1.8m" — not "extra timber work".
2. When. The date it was agreed. A text message timestamps itself, which is one reason texts beat verbal.
3. Who. The person who agreed. This matters more than it looks: the tenant, the site foreman or one half of a couple may not be the person who pays the invoice. If the agree-er isn't the payer, get it in front of the payer.
4. Price. The amount, plus whether it includes GST. If you can't price it yet, say so explicitly: "can't price until the wall's open — will confirm before proceeding" is a record; silence is not.

Get the yes in writing before you start

The strongest position is a written acknowledgement before the extra work happens. It doesn't need a signature block. A text that says "As discussed: replacing the rotted joist while the floor's up, $650 + GST on top of the quote — OK to proceed?" and a reply of "yep go ahead" is a dated, written agreement from the right person. It converts the extra from "thing you claim happened" to "thing they asked for in writing".

If the job is under a domestic building contract, be aware that most Australian states have statutory rules about how variations to that contract must be documented and approved, and they can be stricter than a text message. The rules differ by state and by contract — check what applies to yours. For what a formal variation document should contain, see what to include in a building variation.

Photos: cheap evidence, take them anyway

A photo of the rotted joist, the corroded pipe, the non-compliant wiring — taken before you fix it — does two jobs. It supports why the extra work was needed, and it timestamps the discovery. Take a wide shot for context and a close shot for detail, and take them before and after. Thirty seconds of photos is the difference between "trust me, it was bad" and showing them it was bad.

A worked example

When the work genuinely can't wait

Sometimes you can't get a yes first — a live leak, an unsafe circuit, a hole in the roof with rain coming. Do the work that safety or damage-prevention requires, and document it the same way, as close to the moment as you can: photos of the problem, a note of what you did and why it couldn't wait, and a message to the customer the same day telling them what happened and what it costs. "Same day" is the standard that keeps you credible; the record you make at knock-off time still beats the one you reconstruct at invoice time. And keep the emergency scope tight — fix what can't wait, then get agreement for the rest.

Common mistakes

• Saving it all up for the invoice. One big surprise at the end guarantees a dispute. Each extra should reach the customer when it happens, not as a line-item ambush.
• Recording it only for yourself. A note in your own phone proves what you remembered, not what they agreed. The record has to reach the customer.
• Vague scope. "Extra plumbing work — $700" invites the question "what plumbing work?". Specific scope is what makes the price look reasonable.
• Leaving GST ambiguous. "$480" that you meant as plus-GST and they heard as total is a $48 argument you created yourself.
• Getting the yes from the wrong person. The tenant's approval doesn't bind the landlord who pays.
• Doing nice-to-have extras on emergency footing. "It couldn't wait" only covers what actually couldn't wait.

Where TradieCue fits

Everything above works with a text message and a camera — no app required. The failure point is discipline: the record has to be made in the thirty seconds you're standing next to the problem, and most days that's exactly when you don't feel like typing. TradieCue exists for that moment: say the extra out loud — "Sarah's deck, two rotted stumps, $480 plus GST on top" — and Timmy drafts a written variation linked to the right job. The price is yours: you said $480, the draft says $480, and Timmy never invents an amount. Nothing is sent automatically. Every quote, variation and follow-up is a draft the user reviews, edits and shares themselves. You review it, then send it your way.

It won't make the record legally bulletproof — no tool can, and drafts aren't legal advice — but it makes the good habit cheap enough to keep on a bad day. See variation capture for how it works, or start from the free building variation template if you'd rather do it on paper.

Common questions