Getting a quote out fast matters — but getting the GST on it wrong matters more, because whatever's on the quote usually ends up copied straight onto the invoice. For Australian trade businesses, that's the moment a small rounding or treatment mistake turns into a real accounting headache at BAS time.
The 10% GST rule, in plain terms
If you're registered for GST, you charge 10% on top of your taxable supplies — most trade work falls into this category unless you're specifically supplying something GST-free. The two numbers that matter on a quote are the GST-exclusive price (what you actually earn) and the GST-inclusive price (what the customer pays) — a quote that only shows one of them, or blends them inconsistently across line items, is the single most common source of confusion once the job's done and it's time to invoice.
When you need to register for GST
You must register for GST once your business turns over $75,000 or more in a financial year (a lower $150,000 threshold applies to non-profits) — but plenty of sole traders register voluntarily well before that, because it lets you claim GST credits on tools, materials and vehicle expenses. Once you're registered, every taxable quote and invoice needs to show GST correctly — there's no "figure it out later."
Common mistakes we see on trade quotes
- Applying GST to the whole quote total instead of per line item, which breaks down the moment a customer asks for one item removed or changed
- Rounding GST inconsistently across line items, so the quote total doesn't reconcile to line-item totals
- Not clearly labelling whether a price is GST-inclusive or GST-exclusive, which is a common source of disputes when the invoice arrives
- Forgetting to show your ABN on the quote at all — not a GST issue exactly, but customers checking your legitimacy will look for it
How SJMS handles this automatically
SJMS's quoting calculates GST per line item automatically as you build the quote — add a description, quantity and unit price, and both the GST-inclusive and GST-exclusive totals are worked out for you, consistently, every time. When the customer accepts, that same quote converts straight into a job, and later into an ATO-compliant invoice with the GST math and BAS period tagging already sorted. See Create and send a quote in the Help Center for the exact steps.
Getting GST right on paper is one less thing to think about on-site — and one less thing your bookkeeper has to chase you about in July.