Manual discounts will apply the discounted price when you click the Apply Discount button to an eligible customer's invoice.
To first set up, go to Settings > Invoice Options > Payments & Discounts and select Manual Discounts followed by clicking the Update button. To set up your customer’s discount rate, go to Customers > Select the customer > Options tab > Enter in the discount rate that this customer should get and use the tick box to decide if the discount should be shown on the invoice > Click Update.
Applying the Discount
To apply a discount to a customer’s invoice, generate an invoice for the customer as normal. You can then press the Apply Discount button that will subtract the percentage due against the total net amount and show as a negative line. Please note that if you only wanted to discount certain items you should enter those first, then apply the discount, then add the subsequent line items. You can only use the Apply Discount button once on an invoice.