Payment terms are the length of time that a customer has to pay your invoices. This number, in days, is the length of time after the invoice date or month end the payment needs to be paid by. This will be the payment due date. For example; payment terms of 14 days and the invoice issue date is 01/01/2013, then the invoice due date with be 15/01/2012.
Global default for all customers
You can define the default payment terms for all new customers in Settings > Company Details. Use the Payment Terms text and drop down box to define how many days after the invoice date or month ends the payment due date should be. When you’re done, click the Update button. Please note that this will only affect new customers that you create. Existing customers will still have their original payment terms in their company profile. For information on changing these, please see the guidance below.
Per customer basis
To define individual payment terms for your customers, go to Customers > Select the customer > Options tab > Use the payment terms drop down to select how many days after the invoice date/month end. When you’re done, click Update. Please note that this will only affect future invoice for this customer. Invoices that have previously been raised will not be affected. To modify the payment terms on an existing invoice you will need to edit the Invoice Due Date. If you would like to change your payment terms for all new customers you create, please see the guidance on changing the global default payment terms please see the information above.