GST trips up more New Zealand tradies than almost any other part of running a business. Get it right and it's just admin; get it wrong and you can end up owing IRD thousands you've already spent. This guide covers what every NZ tradie needs to know about GST in 2026 — when to register, how to file, and the mistakes that cost real money.
The $60,000 GST threshold
You must register for GST once your turnover passes $60,000 in any rolling 12-month period — or as soon as you reasonably expect it to. For a full-time tradie charging by the hour, that threshold arrives fast: even at $45/hour, you'll cross it well before the end of a busy year.
You can also register voluntarily below $60k. That's worth doing if you're spending big on tools, a work vehicle, or materials, because registering lets you claim the GST back on those purchases. For more detail on the trade-offs, see our GST registration guide for tradies and the should I register for GST breakdown.
How GST works once you're registered
Once registered, you add 15% GST to every invoice and quote. That extra 15% is not income — it's tax you're collecting on IRD's behalf. You then file a GST return and pay IRD the GST you collected, minus the GST you paid on business expenses.
Most tradies file two-monthly, which is the default and a good balance of admin and cash-flow control. If your turnover is under $500,000 you can file six-monthly, or go monthly if you'd rather reconcile more often. Use our free GST calculator to add or remove 15% on any figure in seconds.
Common GST mistakes to avoid
- Spending the GST. The single biggest mistake. Move 15% of every payment into a separate account the day it arrives so it's there at return time.
- Losing tax invoices. You can only claim GST back if you can prove the expense. Keep every receipt — photograph them if you have to.
- Forgetting the deadline. Late filing means penalties and interest. Add your GST dates to a calendar; our NZ tax dates calendar lists the key ones.
- Claiming personal spending. Only the business-use portion of mixed-use costs (like a vehicle or phone) is claimable. Getting greedy here is exactly what IRD audits look for.
Stay on top of those four and GST becomes a routine task rather than a nasty surprise. For a wider view of tax beyond GST, read our NZ tradie tax guide for 2026.