Hi - when I receive payment for an invoice do I add GST or mark as exempt (as GST would have been already paid)

Hi there,

Making sure you're recording your transactions the right way is a good exercise for preventing errors in your books. 

I recommend contacting an accounting professional to get more info on this. If you're not in contact with one, I encourage you to search for one on our website using this link here. Doing this will help prevent any future discrepancies. Let me know if you have other questions. I'm here to help.