Would a ARM loan with a fixed initial premium or discounted rate that will change to a variable rate based on a margin and index be considered an irregular transaction?

Late in 2012, I wrote a white paper on Reg Z's "irregular transactions" rules. BOL placed it in Tools or some other resource collection, but now I can't find it. If it's still on the site, maybe someone can post the link here for future reference. For now, I've posted a copy at http://aprsystems.com/22a3.doc.

The short answer is: it depends on what the loan's payment schedule looks like (when you apply the rules from Section 1026.17(c)(1), OI #10) on a cash flow diagram.