If a bank mails an interest check off of a CD to a customer and the check is returned undeliverable every effort is made to determine any new/appropriate address. If no revised address is found can the check be voided, and the interest added back to the CD or should it be held until the time of escheatment?

The check is subject to escheat.

[Please don't tell anyone, but if I would be tempted to add the amount of the check back to the time deposit and reset it so future payments are added back to the principal. I'm not trying to cheat the state as I assume there will be some point where the deposit itself (plus the interest added back) will be subject to escheat. I would make certain that my auditor knew what I was doing and the trail was clear.]

Just another reason to get rid of CD interest checks....