Foreign Currency valuation reversal posted to end of the Month

Hi

The Foreign Currency valuation reversal entry is usually posted to the first of every month. In our company it is being posted on the last calendar day of the month.

Kindly explain why it is posting on the end of the months instead of the first.

The user does not given reversal posting date  Reverse Post period and Reverse postings are unchecked in transaction F.05

Thanks