GST Calculator NZ
Add or remove 15% GST on any amount — instantly.
Open tool →Practical calculators and generators built for New Zealand plumbers, electricians, builders and every trade in between. Work out GST, build an invoice, calculate the interest on an overdue payment, or generate a letter of demand — all free, no sign-up needed.
Work out the interest you can charge on an overdue invoice.
Open tool →Generate a firm, compliant final-notice letter for an unpaid invoice.
Open tool →Create a CCA 2002 payment claim or payment schedule for construction work.
Open tool →Most NZ trade businesses lose hours every week to admin — quoting, invoicing, working out GST, and chasing late payments. These free tools take the friction out of the jobs you do over and over. They follow the order that actually gets you paid: get the invoice right, set clear payment terms, and act fast when a payment goes overdue.
If you'd rather not chase invoices by hand at all, compare job management software — the good ones send the reminders for you.