An option to waive accrued/applied interest on revolving credit loans if principal is received after X number of days, or by a specified date.
Credit card companies typically waive interest (fully or partially) if the principal balance is repaid by a certain point in time.
For example, it could be that interest is waived if the principal is repaid before the regular repayment day. If this is the 30th of every month, a customer draws out (spends) €500 on the 5th, but repays it in its entirety on the 20th, the 15 days' interest will be waived and the customer will not be expected to pay anything on the 30th.
Another example could be that the customer is not expected to pay any interest if all principal is repaid within 20 days. If we consider the above example again, the customer will not be expected to pay interest if the €500 drawn on the 5th is repaid before the 25th.
This should be presented as an option because, although it may be a common practice with credit cards, other revolving products such as loans could function differently, whereby interest is always expected to be repaid.