I have the same problem. The Activation screen is blank. Can someone from Intuit answer this question PLEASE.

I am having this same problem.  Has Intuit sent an answer?

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The activation screen for 2021 is blank. Where do I enter the activation codes?

I tried all the "Intuit"solutions with no resolve.  When is intuit going to send down a patch to make Windows 11 compatible with their software so we can do our 2021 taxes on Turbo tax?  Please advise with detailed instruction a person with minimal computer ITT experience can handle.  It would be much appreciated to get an answer from intuit we can use.

THANK YOU TURBOTAX:  I had the same problem and they sent me an update which allowed me to enter the code and all is well.

I had this same problem a year ago and don't recall where I found the solution, nor what the actual solution was, just recall that it was something simple.  Now having same problem with 2021 TT.  Called helpline, which was zero help, zip, nada -- the girl I talked to even said she was asking for help from someone else, then said to expect a call-back in a few minutes, and that was over an hour ago.  Since I recall it was a simple solution a year ago, started trying simple things -- first went into computer settings and changed resolution to 600 x 800 or 640 x 840 or something, no luck.  From here it's confusing because I tried several things and got activated and running TT.  I think what I did finally was right-click on my TT icon for Properties, then went to Compatibility, then clicked boxes to override my computer settings and use the TT application settings, saved, clicked okay, then opened TT.  After finally getting into TT, then exited out and re-set back to original settings, and re-opened TT and it works.  Still no call-back for TT help folks.  Hope this helps someone.  To actually list all the details of what I did, I would actually need to do them and right down each step as I went, but it was simple, just aggravating.  I'm not very computer savvy.

I can’t install TT 2021 on dell xps 9570 windows 11.  I get to where it asks me if f I want to let it change the computer, where I answer “yes” and then nothing after that.  Did all updates etc.  talked to 2 TT tech people who had no idea what to do.  Said talk to Microsoft.  What a bunch of s#%>>>.  Any ideas?  Tried with CD and online and both did the same thing.

My original issue was after installing TT '21, I'd make it all the way to the activation window only to find it blank. After an hour of aggravation and research, I piecemealed this solution together which ultimately worked: (1) disabled all antivirus/firewall apps temporarily; (2) changed the display resolution to 800x600; (3) changed the application settings to launch as administrator (right-click app/properties/compatibility); (4) got the blank window, changed the display settings back to my original 1920x1080, which magically now showed a field to enter the activation code in; (5) however, trying to enter the code in the field was futile as no cursor shows up; click into the field as if you were going to enter the code, carefully/blindly enter the activation code INCLUDING dashes; (6) click on activate TT and voila! you get the next registration window. OMG, this was such a waste of time and disappointing having been a decades-old user of TT - never experienced anything like this before. Hope this helps all y'all! 

Had the same issue:  a blank Activation screen.

Using a new Surface Pro 8 with Windows 11.

What worked for me was changing the scaling to 125% and the resolution to 1920 x 1080. 

Other combinations would show some of the dialog box contents but not all, or would not allow input even when the activation code text entry was visible - someone suggested moving the mouse down just in case the graphic and actual input area were misaligned - this did not work.

Other combinations of scaling and resolution would show part or all of the dialog box, but only the combo above worked for me.  I am sure that Your Mileage May Vary.

What Intuit / TurboTax should do is throw together a quick command line tool to allow running an activation from the command prompt.  Since the GUI is messed up anyway and requires this jiggery-pokery to get it working, using such a tool wold be a quick and easy work-around for users and a quick solution for both them and the tech support people.

Hope this helps.