Get every variation agreed in writing

Variations are where margin leaks. Extra work done on a handshake is easy to forget and hard to get paid for. Get a written yes before you start, every time.

Why it has to be in writing first

For most home building work, the law says so. Your contract usually does too.
Without a written record, it's your word against theirs about what was asked for and what it would cost.
The QBCC says variations that aren't properly recorded and approved before the work are one of the most common causes of serious building disputes.

What the rules say in your state

NSW: a home building contract over $20,000 must say that any agreement to vary the contract or the plans must be in writing and signed by you and the homeowner.
Victoria: you and your client must agree to the change in writing. The details, including the new price and completion date, go into the contract before the work is done. You don't need a variation notice if you reasonably believe the change won't need a permit change, won't cause a delay and won't add more than 2% to the original price.
Queensland: before you start the variation work, you must give the homeowner the variation in writing, and they must agree to it in writing. You can't ask to be paid for a variation before that work has started.
Other states and territories: home building contracts have their own rules. Check your building regulator and your contract.

Victoria's new building contract laws take effect by 1 December 2026. They bring in one simple process for variations on major domestic building contracts, whoever asks for the change. Check Consumer Affairs Victoria for the latest.

On commercial jobs and subcontracts, your contract sets the process. Read the variation clause closely. Some contracts have time limits for giving notice of a variation or delay, and you can lose the claim if you miss them.

What to record for every variation

What's changing. Describe the change. Add a sketch or photo if it helps.
Why. Client request, a site condition, or something the certifier or council needs.
The price. The cost including GST, or how it will be worked out.
Time. How many extra days it adds, if any.
Who asked and who approved. Their name, and that they can approve it for the client.
Dates. When it was asked for and when it was approved.
When it's paid. For example, with the next progress claim.
Evidence. Photos, emails, drawings and site notes.

In Queensland, the written variation must include the description, the date it was asked for, your estimate of any delay, the change to the price, and when the extra is to be paid or the credit given.

Footing's variation register records the reason, the cost including GST, the Extension of time and your evidence for each one. Approved variations are added to the contract sum, so your next progress claim picks them up.

When it's urgent and they say “just do it”

Sometimes work can't wait: a safety issue, a storm coming, a burst pipe. Some states' rules have a narrow exception for genuinely urgent work. Don't treat it as the normal way of working.

Make it safe first.
Confirm in writing straight away.
Text or email the client: what you're doing, why, and the rough cost. Ask them to reply “yes”.
Record who said yes and when.
Send the formal variation for signature as soon as you can.

In Footing, clients can approve a variation online with a signature. If they said yes by phone or email, use Record approval to log it with the approver's name. Then get the signed variation too, if your contract or state rules need one.

Don't start varied work without sign-off

If you do the work first and talk price later, you're relying on goodwill to get paid. Make the rule simple for everyone on site:

No variation work starts until the office says it's approved.
Crew and subbies send change requests to the office, not straight to the client.
Price it, send it, get the yes, then build it.

Sources

Checked September 2026. Rules change, and they differ between states. This is general information, not legal or tax advice.

Raise a variation and get it approvedRecord a change to the price or time and get your client’s signed approval.5 min Quotes that protect your marginWrite quotes that say what's in, what's out and what could change, so the price you win is the price you keep.5 min Security of Payment: how progress claims get you paidThe basics of Security of Payment laws: payment claims, payment schedules, deadlines and adjudication, and how each state differs.5 min

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