The TurboTax online editions for tax year 2019 should be available on December 4.
You can file a 2019 tax return after January 1, 2020. However, the IRS will probably not be accepting any type of 2019 tax return until late January.
The TurboTax desktop CD/Download editions for tax year 2019 are currently available - https://turbotax.intuit.com/personal-taxes/cd-download/
The IRS has NOT announced a starting date for processing any of the 2019 tax returns as of this posting.
Although TurboTax will allow you to e-filed some returns as early as 1/2 they are NOT sent to the IRS. TurboTax stores those early filed returns until the IRS opens for business and pulls the returns for processing ... only then will you get an e-mail telling you if the return was accepted or rejected by the IRS.
Only the simplest returns can be transmitted to TurboTax early. Some forms will not be finalized until Jan 25 and some later than that.
Why does TurboTax allow early filing? Because their competitors do - It is a marketing ploy to capture market share.
Filing early with TurboTax before the IRS opens is a really BAD IDEA for many reasons...
1) If you discover something that is wrong on your return, receive a W-2 that is different, receive some other tax document that was not on the return that you filed then there is NOTHING that you can do about it other than wait to see if the IRS accepts or rejects the return after they open. If rejected you can correct and file again, but if accepted then the only remedy is to amend which can take 4 months to process.
2) You must remember to check back after the IRS opens (or check for an e-mail) to confirm that the IRS has accepted or rejected the return. If rejected, then it was never filed at all and must be corrected and re-filed. Every year many taxpayers that file early, forget to check back and only discover months later that they never actually filed because if was rejected by the IRS but they had forgotten about checking back after filing with TurboTax.
3) While the IRS does conduct some pre-opening tests and does accept some returns early (ONLY for TESTING purposes), they will not actually process those until after the official opening date. There is a reason to test and that is to discover any problems with it's systems. A couple of years ago a test went bad and several thousand "test" returns were lost. The IRS was able to recover those but it delayed refunds for some by months.
There is no real advantage to file before the IRS opens but there are several disadvantages to do so.