Invoice requirements checker
Pick the country and the order total (GST inclusive). You'll see which details the invoice has to show.
Plain-language rules: NZ guide · AU guide
Kiwi GST Invoices is a Shopify app we're building that prints NZ and AU tax invoices with these fields filled in from each order. It is not on the Shopify App Store yet (it hasn't been released).
Based on GST Act 1985 s19K and the ATO. Not tax advice.