Bad debt should be posted in the month of write off.
Currently bad debt is posting in date of order.
Yes, this is a fair complaint. We're also not happy about how CMS handles bad payments/debts.
We had planned to include related enhancements in 10.0 but the extent of the PCI related changes forced us to trim some of the planned features out.
Hopefully these enhancements will get into the next release after 10.0.1. A number of votes here could help ensure that happens.