Why does the system request the amount of GST?
Most companies can claim a refund of GST paid to other suppliers. By entering the GST, the amount entered will automatically appear as a debit to Accounts Receivable - GST. If not eligible for GST, do not enter in the GST amount.
Do I need to include invoice details with every Customer Specific payment?
Invoice details must be entered for customer specific payments. If you do not have an invoice number, you can say "Payment on account" or provide any other explanation you wish.