Generally, the TTX program for the next tax filing year is available for purchase/download anywhere from the last week of November (around thanksgiving) to the middle of December. But history indicates that the program is usually not complete, meaning you may not be able to complete the tax return as you might like to. This is because Congress has not finalized tax law changes, as well as the IRS has not released/approved the official electronic forms to vendors for inclusion in their software. Next, history also shows that the IRS doesn't even open up their computers to accept e-filed returns until after the first week of January. Heck, one year they didn't open e-filing until the last week of February.
So if you think filing early means you will get your refund sooner, don't count on it. The IRS does not process returns as first in first out. For example, for 2020 tax returns if you qualified for and claimed the EITC, the IRS could not issue the refund until the first week of march, regardless of how early you may have filed. My understanding was that an earlier payment was forbidden by tax law, or something like that.
Additionally, if you e-file your return before the IRS computers are ready to process it, then it just "sits there" on the server until they start processing. Meanwhile, if you find a mistake that you need to correct, you can't do jack squat until "AFTER" the IRS has either processed your return and you have received your refund, or the IRS computers reject your e-filed return. So there's really no benefit for a majority of tax filers just because they e-filed early.
I myself never e-file prior to March 1st. This is because I wait for errors to be found and fixed in the program so as to increase my confidence in the accuracy of my e-filed return. I've been using TTX for over 15 years now, and there hasn't been a year go by that errors are not found and fixed by the programmers on a weekly basis during the tax filing season.
