I had the exact same error message with my 2019 California return. Fortunately, your solution worked for me and I was able to file my return today - Question: Why hasn't TT fixed this known error for 2019?

Still a bug for 2020, too.

still a bug for 2021

Still a bug for 2022

Hi Rabbitball, How do you enable a CA 3510? It seems that I can't even enable this anywhere from TurboTax Live Premium online? I am pretty sure I have AMT last year 2021, and I have Form 3510 Generated as well last year

When you complete the California interview in TurboTax Online, the Prior Year Alternative Minimum Tax Credit should appear among the choices on the screen "Take a look at California credits and taxes", which appears after the screen "Adjustments and Preferences: California". It is also listed as a choice in TurboTax Desktop.

If you have gone through the whole interview and seen the California credits screen, and the Prior Year Alternative Minimum Tax Credit isn't listed among the choices, try logging out of the program and logging back in. Consider trying another browser. If the problem persists, you could delete the California return and add/complete it again.

See this tax tips article for answers to common questions about AMT.

Thank you so much for this response! I was stuck on filing my taxes until I saw this.

But why doesn't TurboTax just fill this out directly? It's a huge pain for us to fill this out and they should be able to pull it in from last year's taxes.

Also, why don't they make it easier for us to figure out how to fill out that field instead of making us come to the community to find out? It took me an hour before I found your answer here, after first doing research online, calling support, etc.

Appreciate your help!

I do see this "Take a look at California credits and taxes" however, the "Prior Year Alternative Minimum Tax Credit" is not listed there as an option... (It was in my last year's option here in the same place though). Do I have to fill in something in the previour interviews in order to trigger this option?

I asked several experts via live help, however none of them is able to tell me the answer -- one of them said it could be a bug and she will report it to the Technical team, however there is no estimation time of fix.

First time I feel so frustrated using Turbotax.

I found the choice displayed in both Online and Desktop as per my earlier response. 

If you haven't already - I suggest taking these steps:

If you have gone through the whole interview and seen the California credits screen, and the Prior Year Alternative Minimum Tax Credit isn't listed among the choices, try logging out of the program and logging back in. Consider trying another browser. If the problem persists, you could delete the California return and add/complete it again, and look at each interview screen.

If the problem still persists - in order for us to troubleshoot this issue, you can send us a “diagnostic” file that has your “numbers” but not your personal information. If you would like to do this, here are the instructions for TurboTax Desktop users:

Go to the black panel on the left side of your program and select Tax Tools. 

1. Then select Tools below Tax Tools. 
2. A window will pop up which says Tools Center.  
3. On this screen, select Share my file with Agent. 
4. You will see a message explaining what the diagnostic copy is. Click okay through this screen and then you will get a Token number. 
5. Reply to this thread with your Token number. This will allow us to open a copy of your return without seeing any personal information.  

You are a life saver. Thank you for this golden tip. I was going crazy until I saw your solution to the problem. It works perfectly for my Year 2022 Return. Thank you so much! This is like magic.

This is still an issue on the TurboTax Desktop product (at least on the Mac).  Last year I tried following the directions given here and gave up and just printed out the taxes so I would manually put a "0" in Line 28 and get it filed. 

Turbo Tax knows about the Prior AMT. On Form 3510 it knows what the carry over was from last year. It it giving the appropriate credit for this year. It even gives me a "Prior Year Alternative Minimum Tax Credit" line item up in the blue highlighted area, BUT when I click the Edit button it simply (correctly) informs me what the credit for prior years has been and what my carry over will be to 2024, and then a Continue button which just takes me out of that section. There is no opportunity to say what should go into line 28 there.

And still... While the software tells me that Line 28 needs something filled in, and it highlights that field, it is not editable. 

I can't believe how many years this has been an issue. Just let us edit that field. Or take us to the correct portion of the product to be able to answer a question about what goes in that field.

I guess I'll just save myself the $20 for e-filing and print it again and manually put a 0 in that field. Annoying, but you are forcing me to pay you less money so I suppose I should be thankful for that.

I just tested the issue you reported, using TurboTax Home and Business for Mac. I found that you can go into Forms mode and enter data in any of the non-computational lines on Form 3510, except Line 28.

I will report this issue for further review. Please post again if you have found anything else not working with Form 3510.

Update: This is an identified issue. Users who wish to sign up to be notified of progress on this issue can do so here.

[Edited 03/31/24| 5:49pm PST]

@matteartist