I'm talking to a guy tomorrow who runs a biz in a similar field (sole trader) but the input of others can't hurt. One question:

- do I still need to put "Tax invoice" on it even if I'm not GST registered?

As you should not have included any tax on the invoice, I would think that there was no need for it.

No.

Cheers guys

You should still write an invoice though, but no GST registration or GST amount

Another question has come to mind, do I need to list my IRD number on it? The sample I'm using (anyone have better examples let me know) is www.nztecho.com/uploads/File/NZFVTG_Sample_Invoice.pdf

EDIT: okay, I do.

it can't show any GST amount(charged) as your not registered.

ird example
http://www.ird.govt.nz/resources/4/...llustration.gif

Tax Invoice means invoice. and the customer may claim the amount in their tax, if a business. GST is another thing altogether and may or may not be included on the invoice depending on if the supplier or tradie is GST registered.