POP Transaction Guidance

I'm on the road and do not have access to the NACHA Rule book. We have a situation that has occurred where two electronic checks have cleared our customer's account from November and December 2018. Does the merchant have a cutoff for presentment on these transactions, or are we bound by UCC since the transaction originated with a paper check? Are these now considered stale?

POP transactions are not UCC-covered. They are EFTs subject to NACHA rules. There's nothing in the definition of the "Eligible Source Document" for a POP entry that says anything about stale-dating. Even under the old UCC a check under 6 months old wasn't stale when presented, and in today's UCC, a date more than six months old doesn't mean the check can't be paid.

If your customer decided after a couple of months without the transactions clearing that they wouldn't be presented, he's just had a rude awakening after having the use of that extra money in his account for 5 or 6 months.