Can someone explain to me what a proforma invoice is and what the purpose of it is.

I am in the accommodation business and issue a proforma invoice to clients to do pre-payment. Then, when I receive the payment, I issue a Tax Invoice. That is my understanding.

I however get clients that refuse to pay on said proforma invoice. Who needs to be educated?

I do not issue Tax Invoice before payment, as I am used to help defraud companies. People book, never stay, or pay, and use the invoice to claim from their company.

It is in the latest case actually the accounts department of a company that insist on a Tax Invoice before payment.