Just got off the phone with THE Man himself, Franklin Argentine, at the Michigan Department of Treasury - Aircraft Unit, Discovery and Tax Enforcement. My mind has been set at ease! It was a very pleasant conversation, Franklin is a very amicable and talkative gentleman. I got the phone number for their department from form 1989. (Thanks Brian and David)
He said if I wanted, I could self-report now with my reserved N-number, pay the tax on the kits I've bought so far (or show that I already paid on my MI-1040 or on a Van's invoice) and I would never hear from their office when I do actually register the plane because they would already have a record for it (unless I change the N-number, or register the plane under a different name or corporation). For the remainder of the kits, I would still be liable for the use/sales tax, but that would be handled through Van's if they start collecting, or through my MI-1040 if not; his office would not get involved.
He also stressed that they're only concerned about the big stuff, so don't try to keep records of every extra rivet purchased. They aren't going to argue over a couple hundred bucks worth of tax revenue from a homebuilder, they've got much bigger fish to fry. Along those same lines, he said there would not be any equalization tax; they consider the purchase price to be the fair market value for tax calculation.
To self-report with their office, he said to use form 1989 if you still owe some tax, or form 4281 if you've already paid all your use/sales tax and have the invoices and/or tax returns to back it up.
Van Buren TWP, MI
Student Pilot, Mechanical Engineer
RV-12iS Empennage, Fuse, Finish, & Avionics Kits #121228