I freely admit I know nothing about this whatsoever, so here is my opinion: Why not get rid of GST altogether? It is a crappy tax that hits the poorest the hardest and most people probably resent paying it. Replace it with a financial transaction tax. Few if any overseas purchases are done in cash. Illegal drugs, maybe, but they don't pay tax anyway. So just slap an automatic tax on any electronic payment, credit card, debit card, whatever, wherever. Problem solved?