Even those who don't receive their Teslas before the year ends can still take advantage of the $7,500 federal tax incentive in full. That tax credit will still be halved when the clock strikes midnight on New Year's Eve. However, company chief Elon Musk has announced on Twitter that the automaker will cover the difference in case it can't deliver in the next few days if it said it would -- so long as the "customer made good faith efforts" to receive the vehicle before 2019. It's not entirely clear what he means by "good faith efforts," but it could simply be a case of being available to receive the delivery this holiday season.