Hi Sylvia,
Thank you for using Dynamics 365 Finance Communities.
Interest note Reversals will use the posting date of the Interest note.
In this example, if the Interest note was posted in 1/1/2020, then the reversal will be posted in 1/1/2020 as well similar to the example below:
Original Interest note posting date 1/1/2020

Reversal posting date is 1/1/2020 (NOTE: system date is 5/5/2020)

The same applies even if you run the reversal process in a different period (system date). The system will still use the original posting date of the Interest note for the reversal posting date.
In your example, if the Interest note was posted in May and the reversal is processed in June, the reversal date will still be in May as this is when the interest note was posted.
Hope this helps. If your question has also been answered, please help mark the thread as answered.
Regards,
Marian Wrice
SR Support Engineer
Dynamics 365 Finance