The next few months could be difficult for Rivian (RIVN 1.02%). Federal tax incentives for new electric vehicle (EV) purchases could soon be eliminated. Plus, there's another little-understood federal incentive program that could wipe out hundreds of millions in "free" profit for nearly every U.S. EV manufacturer.If all these incentives are eliminated, we could see Rivian stock fall below $10 per share. If this happens, should you jump on the chance to buy? Absolutely, but there are a few things to keep in ...