GST on trade quotes: getting it right.

Do you actually need to register?

The threshold in Australia is $75,000 in annual turnover. And it hasn't moved since GST was introduced in 2000. Once your turnover reaches that, or you reasonably expect it will, you must register within 21 days; the ATO checks both your turnover for the current month plus the previous 11 months, and your projected turnover for the next 12 (source). Below that, registration is optional. And can genuinely be worth doing anyway if your clients are GST-registered businesses who can claim back what you charge them, or if you have real GST-included expenses you'd like to claim back yourself.

Inclusive vs exclusive: two ways to say the same job

Once registered, GST is 10% either way. The only choice is how you present it on the quote. Quoting GST-inclusive shows the client one final number, with the GST folded in (divide that number by 11 to find the GST component). Quoting GST-exclusive shows your price, then GST added as a separate line, then the total. Neither is more "correct." Trade and industry norms vary. But the number needs to be right either way, and it's a common place for manual quotes to slip, especially switching between the two mid-job.

The mistake worth avoiding

The error that actually costs money isn't picking inclusive vs exclusive. It's being inconsistent about it. Quoting a client GST-inclusive, then invoicing GST-exclusive by habit, either undercharges the client or eats into your margin without anyone noticing until it's too late to fix. Whichever method you use, the safest approach is to apply it the same way, every quote, without relying on remembering which one this client got last time.