A check is written out to a business AND the owner, ex: ABC,Inc or John Smith. Can John Smith present the check for cash or must it be deposited into the business account? Also if the names are stacked on top of one another, ex: ABC, Inc
John Smith
What are the requirements when this is presented for payment?

If the word "OR" appears between the names, it's clear that the check can be negotiated by either payee. Whether your bank will allow Smith to cash it may be affected by policy, but he should be able to deposit it to his personal account or the account of the business. I don't imagine, though, that you'll see that sort of check very often.

If the names are stacked and there's no conjunction between them, the intent of the check's issuer is ambiguous. The UCC directs in such cases that you can treat it as if "OR" appears.

Take care, though. Sometimes the second name is preceded by "c/o." That stands for "care of," and is a signal that everything that follows is part of the address instruction on the check, and the name after "c/o" is not a payee.

I should add here that many banks have policies that require all named payees to endorse a check when it's ambiguous whether the payees are named alternatively or not. That's the bank's right, since it's not required to accept the check for deposit or cashing other than on its own terms.

Our bank policy is to require the endorsement of both payees in "stacked" situations. This would be particularly true for a check payable to a business and individual where no "and" appears between the names.

That's a good illustration of my closing point above. I imagine that there are more cases in which an individual is named first and the business second than the other way around.

One other thought. The reason that banks often impose a stricter endorsement standard than the UCC requires doesn't necessarily mean that courts interpret the rules in the UCC differently (although it's possible). If Jeff's bank, for example, slipped up and only got one of the stacked payees to endorse a check, the odds are in the bank's favor if the other payee files a claim. But even the fact of the claim creates a cost for the bank, and it's often easier to eliminate the risk of such a claim than to defend it.