It's not illegal to postdate a check, unless you're attempting to commit fraud.
They should watch for the check to arrive and only cash it if the date you've indicated has passed.
Any check that's properly made out and has your signature is treated as legal tender, and the bank is free to hand over the money to the holder of the check.
There is, however, one situation in which a bank can be held liable if they cash a post-dated check too soon.
While it may be possible to cash a check that's more than 6 months to a year old, there are several things consumers need to consider before heading to the bank with Nana's old checks.
Image Source/Photodisc/Getty Images First things first: There is no hard-and-fast rule about when a check becomes expired.