In the Home window, click Vendors & Purchases on the navigation pane.
In the Tasks pane, right-click the Vendors icon and select Modify Vendor from the menu.
Select a vendor from the list and click OK.
Click the Options tab.
In the Early Payment Terms section, enter:
the
discount rate
the number of
days within which an invoice must be paid to receive the discount
the number of
days within which the full amount of an invoice must be paid
(Optional) If you want Sage Simply Accounting to calculate the discount without including the sales tax,
select the Calculate Discounts Before Tax
check box.