I believe from reading Jack’s response above, you would not include it as a prepaid finance charge initially. After all, how will you know that you’ll be doing a modification or extension when you initially make the loan?
I personally would recommend not charging a fee; as that leaves everything simple, clean, and limits what you’ve done being questioned by auditors and examiners. That being said if you do charge a fee, you might look at just doing a new note because I think you’ll cause yourself to have to give your disclosures again to ensure compliance.
Jack alluded to this earlier, in that if you make big sweeping changes to the loan, then some examiners are considering this to trigger redisclosure, like in a refinance. I tend to agree with them. If you are making small changes say to the payment date, or extending the loan a couple of months, then I don’t think you’ll have much question if you don’t charge a fee.