When importing items VAT charged at the custom points (upfront or deferred). Upfront you pay the VAT, deferred you don't need to pay, but you have to obtain credit voucher from IRD and submit to custom.
When you sales locally charge the VAT from your customer (if your sales liable VAT). BUT if your sales turnover bellow the threshold no need t register for VAT. One quarter exceed threshold limit no need to register. If continually over the threshold register for VAT.
If you're registered for VAT, if one quarter your sales bellow threshold your liable to pay VAT.