From the text of the law itself:
"For purposes of the 30D credit, a vehicle is not considered acquired prior to the time when title to the vehicle passes to the taxpayer under state law."
The law is specific about when a credit counts to the taxpayer, but it's agonizingly vague about when it applies for phase out. I'm not a lawyer, but my SO is, and one of her greatest strengths is parsing laws. She spent years writing appeals and had to parse the minutiae of laws. I haven't asked her to look at this law (she's been swamped this week), but she did teach me a thing or two to look at.
Frequently laws will have omissions regulatory agencies will have to parse. The IRS does with tax law quite frequently. Laws hinge on what the definition of various terms are and when terms aren't defined in the law, somebody has to make a ruling on what the definition is.
For purposes of the 200K threshold, there does not appear to be a definition of "sold". However most of the time when something is undefined, but something similar is (as in this case "sold" and acquired") often the undefined term will be lumped in with the defined term. Though that isn't always the case. In some cases this is determined in court and in other cases the regulatory agency issues a clarification.
If there was any determination of the language, I would have expected some kind of public notice.
The problem is it appears the IRS has largely ignored the EV credit entirely. I came across an article from 2014 that claimed the IRS was not tracking car sales very well and linked to this page:
IRC 30D Plug In Electric Drive Motor Vehicle Credit Quarterly Sales | Internal Revenue Service
which has been maintained, but only tracks Ford, Mercedes, and BMW. The rest of the data from everyone else is nowhere to be found.
Ultimately we won't know one way or the other until there is an official announcement from someone. Clearly Tesla was working with a better set of data than any of us had and going over by a little bit at the end of the quarter just doesn't make sense for a company that is otherwise competent about these sorts of things.
Because Tesla owns the retail end as well as the manufacturing end, they should be able to control the threshold better than other OEMs that sell through dealers. The Bolts and Volts sitting on Chevy dealer's lots don't count until the dealer sells them, but GM doesn't have much control over when that happens. There was evidence Tesla was slowing some deliveries at the end of the quarter, which is further indication they knew the threshold was close and they were working to stay under for IRS determination.
I'll ask my SO to take a look and give her opinion. I'm still quite an amateur at parsing these things compared to her.
