Sorry it's too late to efile. You have to print and mail it now. Did your first efile reject? Do you have to fix anything?
What tax year is the notice for? It would be very odd to get such a notice for a 2020 return already. Did you fail to file for some past tax year?
Online preparation and e-filing for 2018 and 2019 and 2020 is permanently closed.
To file a return for a prior tax year
If you need to prepare a return for 2018, 2019 or 2020 you can purchase and download desktop software to do it, then print, sign, and mail the return(s)
https://turbotax.intuit.com/personal-taxes/past-years-products/
You may also want to explore purchasing the software from various retailers such as Amazon, Costco, Best Buy, Walmart, Sam’s, etc.
Remember to prepare your state return as well—if you live in a state that has a state income tax.
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.
Federal and state returns must be in separate envelopes and they are mailed to different addresses. Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.
Note: The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac. It cannot be used on a mobile devic