So sorry but I really cannot answer for TT, I am not a professional tax preparer or a TT employee/contractor, so I don't know if TT would charge extra for efiling in case of an amended return nowadays.
It may depend upon what version of TT you purchased and how you file. When I did this in the past (a few times because of errors found later in forms supplied by financial institutions issuing corrected statements after I filed or when TT didn't have the one form I needed in time), the IRS in one case required the amended return to be filed by mail, I don't remember why, and in another couple of cases I was able to file the amended return via TT w/o additional charge but I had either Premier or Home/Business which allowed filing of multiple returns for the original cost at least back when these amended returns happened. And it could just be in the first case that the IRS didn't change procedures to allow efiling of amended returns until more recently.
In my case my taxes were completed except for the EV charger credit, so it is easy enough for me to just download the forms from the IRS website and file a short amended return if TT doesn't get the forms in time or charges extra for an amended return. The IRS doesn't charge for filing of a paper return--at least not yet LOL! But a paper return does take longer for a refund, and filing a return now w/o the credit will mean even if TT makes the form available tomorrow that you would still likely need to wait to file your amended return until the IRS actually processes your return (I would need to look this up again but in the past this is what the IRS advised but again that may be due to the days of mostly paper returns). So it really depends on your tax situation as to what is best to do--in my case, my refund is large due to circumstances unforeseen and the EV charger credit portion is small compared to the rest of the refund, so rather than wait months for a full refund, I chose to try to get most of my refund sooner. Just remember the longer it takes you to file, the IRS will start taking longer to process returns because of the backlog as more people file closer to the filing deadline. So filing as early as possible does usually get your refund faster in my experience, so long as your return is correct and doesn't have any significant issues. All this is assuming that you are due a refund separate from whatever credit you may be entitled to under the EV charger credit.
Good luck!
