Explainer
Every state wants the same thing. In writing, before you start.
A variation is any change to the agreed scope after the quote or contract was accepted — and on Australian residential jobs, every state expects it documented in writing before the varied work starts. The details move state by state; the principle doesn't. Here's the national picture, and where each state's rules live.
One principle, five regimes What counts as a variation State-by-state quick reference
01 — The short answer
Extra work, written down, signed before it happens.
On an Australian job site, a variation is a change to the work after the contract was signed: something added, something removed, something swapped for a different material or method — along with its price and its effect on the finish date. It's the paperwork version of “that's not what we agreed”, agreed properly this time.
The reason every regulator, industry body and standard contract keeps saying the same thing about variations is simple: they're where the money disappears. An extra done on a nod has no price anyone agreed to, no date anyone signed, and nothing to point at when the invoice lands — which is why “get variations in writing” is universal advice rather than one state's quirk.
02 — What counts
If it changes scope, price or time, treat it as a variation.
Additions
The customer asks for the carport gutter, the extra power point, the second coat. The classic “while you're here” — and the classic unpaid invoice.
Omissions
The customer takes something out to save money. Still a variation — it changes the contract price, and the credit should be just as documented as the charge.
Substitutions
A different tile, a different unit, whatever's actually in stock. If the price or the spec moves, it's a variation even when nobody thinks of it that way.
Latent conditions
You opened the wall and found what the wall was hiding. Not anyone's fault — but the extra work still needs pricing and signing before it continues.
03 — The process
Four steps, whichever state you're standing in.
Spot the change
The moment scope, price or time moves off the contract, call it: this is a variation. Naming it early is most of the discipline.
Write the one-pager
What changed, why, the price all the way to GST, the days added, and space for both signatures. Our variation letter template covers every box.
Get it signed before starting
No signature, no work — that's not stubbornness, it's what most residential contracts and several state laws actually require.
File it with the job
The signed variation belongs with the quote and the invoices. At dispute time the complete file wins; the loose text message doesn't.
04 — State by state
Same rule everywhere. Different paperwork each way.
Residential building contracts carry a deemed term: agreements to vary must be in writing and signed by or on behalf of each party. Full breakdown in our NSW guide.
Regulated domestic contracts need a compliant written variation document, and the owner's written agreement before varied work starts. Our QLD guide covers Schedule 1B.
Major domestic building contracts run on written variation notices and signed consent — for builder-requested and owner-requested changes alike. Our VIC guide explains ss 37–39.
WA, SA, Tasmania, ACT and NT each have their own building-contracts legislation expecting the same thing: variations documented in writing. Check your state regulator or industry body — thresholds and rules change.
This page is a map, not a ruling. For a live dispute, or anything large or unusual, talk to someone qualified in your state.
Straight answers
Questions people actually ask.
Do construction variations need to be in writing in Australia?
For residential building work, effectively yes across the country: NSW writes a written-and-signed term into home building contracts, Queensland requires a compliant written variation document and the owner's written approval before varied work starts, and Victoria requires written notices and signed consent under its Domestic Building Contracts Act. Other states have their own regimes arriving at the same place. Commercial contracts handle it through their variation clauses instead.
Can I do the extra work first and sort the paperwork later?
You can, and that's exactly how unpaid extras happen. Where the law sets the order — and NSW, Queensland and Victoria all do for residential work — doing it backwards can cost you the ability to claim at all, leaving at best a claim for the reasonable value of the work. Write it, sign it, then build it.
Does a small variation need paperwork too?
Yes — smallness isn't a category the law recognises, and it isn't a category your customer's memory uses either. A two-line written variation takes a minute and settles the question forever. The extras that sink jobs are rarely the big ones; those get treated seriously by everyone.
What should a variation document contain?
The change described plainly, why it happened, the price including GST, the effect on the schedule, and dated signatures from both parties. Some states add specific requirements — Queensland's legislation lists them formally — but that core set satisfies the spirit of every regime and the letter of most.
Method
Where these answers came from.
Vendor screens and features are taken from each publisher's own website or help centre on the date shown. Nothing here is sponsored and no vendor has reviewed this page.
If something's changed, tell us and we'll fix it — an out-of-date guide is worse than none.
The next one's coming
The next “can you just” is already on its way.
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