SAP Note 18013 - RFDUZI00, credit interest calculated using debit interest ra

Symptom:

During the calculation of interest on arrears (RFDUZI00) and the item interest calculation (RFINTITAR), the interest for credit items is calculated using the debit interest rate.

Other terms

F.24, F.2A, F.2B, F.2C
FINT

Reason and Prerequisites

This is NOT an error.

Solution
If a receivable from the customer is due, the interest of the debit item is calculated using the debit interest rate from that point on. If the customer settles the invoice at a certain time X (acc. to cash receipt) and the item is only cleared by separate accounting at the later time of Y, interest may only be calculated up to the time X.
Since the program calculates interest until the day of clearing, the period between X and Y may NOT be debited to the customer. This is achieved by calculating the interest of the resulting credit item using the same interest rate as the debit item starting at time X. Thus the debit and credit interests for the period from X to Y are offset and the customer is not debited interest for this period.
The case is similar if the customer only pays a part of the invoice at the time X. Then you can only calculate interest for the outstanding amount. The amount of the partial payment is also acheived by calculating with the same interest rate as the invoice that is still open. (If the invoice is cleared during entry of the partial payment and a residual item is formed, the problem occurs).
If you do not agree with this logic and you use the item interest calculation (see Note 670117), you can use the GET_INT_SIGN BAdI method to program a separate logic.