Create payment terms with an early payment discount

Open Settings, then Payment terms. Payment terms say how long a customer has to pay an invoice and whether an early payment discount (in German: Skonto) applies.
Choose New payment terms.
Fill Code (a short fixed label) and Name. The code cannot be changed later because contacts and invoices refer to it.
Under Due after (days) enter how many days the customer has to pay.
For a discount fill both Early payment discount (%) and Discount within (days). For plain net terms leave both empty; filling only one is not accepted.
Choose Save. The list then shows each term as a summary line, for example how many days net.
To change a term later, click its row, edit it and choose Save again.