With the expiration of the federal tax credit at the end of this month, environmental policy experts said, there's one less incentive to buy the climate-friendly vehicles, and they're concerned about how Massachusetts will meet its goals for slashing planet-warming emissions. A Massachusetts-funded EV rebate program will still be available after the federal tax credit ends. The federal tax credit has income eligibility limits and requirements for vehicles to qualify. Consumers can also take advantage of lower monthly payments on leased EVs through the expiring tax credit. The other driver of EV sales, charging stations, seem to be back on track.