Variations and approvals
Extra work added without approval: how to check the paperwork
A comparison of two documents can show that an invoice includes work the quote did not. It cannot show whether that work was approved. Those are separate questions, and keeping them separate makes the conversation with your supplier much easier.
QuoteTrace guide · Updated September 2026
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Start with the overall price
Start with the difference the documents actually show: the whole-job total on the quote you accepted against the whole-job total on the invoice, before tax. That figure is the documented difference. Whether each part of it was approved is answered by your variation forms, emails and messages, not by the invoice itself.
What to check next
Check 1
Documented difference is not the same as unapproved work
The invoice can only show that an amount or a line item is different. Approval lives elsewhere: a signed variation, an email reply, a text message, a site instruction or a diary note. Treat the invoice difference as the starting figure and then subtract the parts you can match to an approval record.
Check 2
Gather the approval records alongside the two documents
Collect variation forms, quotes for extras, emails, SMS threads and any written instruction, and put them in date order. QuoteTrace compares the two documents you upload; it does not read these additional files and does not decide whether an approval is legally sufficient.
Check 3
Match each extra amount to a record, or to nothing
Go line by line through the additional amounts. Each one either matches an approval record, partly matches one, or has no record at all. The last group is what you ask the supplier about, and it is usually much smaller than the headline difference.
Check 4
Watch for verbal or implied approvals
Some changes are agreed on site and never written down. That does not make them fictional, and it does not settle who is right. Note them honestly as items with no written record so the discussion is about facts rather than positions.
Check 5
Keep tax out of the approval question
Compare before-tax amounts when working out what needs clarifying. Tax generally follows the before-tax amount automatically, so counting it again as an unexplained increase overstates the difference.
A worked example (fictional figures)
- Accepted quote: A$6,000 before tax.
- Final invoice: A$8,100 before tax.
- Documented difference: A$2,100 before tax.
- Of that, A$500 matches a written approval record, leaving A$1,600 to clarify.
- If both documents use 10% GST, tax rises by A$210 and the total rises by A$2,310 — the same A$2,100, plus its tax. Do not count the tax again as a separate increase.
Questions to ask before paying
- Which written approval or variation covers this additional amount?
- When was this extra work instructed, and by whom?
- Was a price for this extra work provided before it was carried out?
- Can you send me the variation form, email or message you are relying on?
- Does this line replace quoted work, or is it in addition to it?
- Can you show the before-tax amount and the tax separately for each extra?
Common questions
Does a difference mean the extra work was unapproved?
No. It means the invoice includes something the accepted quote did not describe at that price. Approval is proved by your variation records, so the difference is a prompt to check those records and ask the supplier for theirs.
Can QuoteTrace read my emails or variation forms?
No. QuoteTrace compares the two documents you upload: the accepted quote or agreement, and the final bill. Approval evidence is something you assemble and review yourself.
Should I refuse to pay the disputed amount?
That is not a decision QuoteTrace can make for you, and this guide does not advise withholding payment. What applies to your situation depends on your agreement and your jurisdiction; consider getting advice from your state or territory fair trading or building authority, or a qualified adviser.
What if the extra work was clearly necessary?
Necessary work can still require an approval step under your agreement. Ask when it was identified, what it cost, and what record exists of you agreeing to it.
Where to read official guidance
- NSW Government: home building contracts
This is New South Wales guidance only. Requirements for variations and approvals depend on your jurisdiction and on the agreement you signed.
Related: Invoice doesn't match the quote: how to compare them properly
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