I was just able to coax my copy of TurboTax Deluxe 2020 (for Windows) software into completing the California FTB Form 5805 correctly and now my CA State tax electronic filing has been accepted.
I suspect the programming logic for this form in the TTD-2020 "fat client" software needs to be reviewed. Intuit may not consider it to be a bug, per se, but the logic definitely needs to be more bulletproof to prevent end-users like myself accidentally shooting themselves in the foot.
I've used TuboTax for about 20 years without any problems, albeit my tax situation has become more complex over time. However, this was the first time I've ever needed to contact Customer Support, but they were unable to resolve my problem in a timely manner, despite trying their best.
My work around for CA FTB Form 5805 was as follows:
1) Changed my answer to N/A for Part I Line 3 (P1L3") and deleted the values previously entered for the uneven withholding amounts. (the question for P1L3 is itself confusing because it uses negative logic).
2) Manually entered my CA 2019 tax amount into the field for Part II line 5.
3) Retained the text in the P1L1 Waiver Explanation field and also all the data in Part III (Annualized Income Installment Method) entered previously.
4) Entered "Waiver" as text into the leftmost field of Part II Line 13
5) Entered the numeric value of the Estimated Tax Penalty ( found on line 14 of 5805 Wks II ) into the rightmost field of Part III Line 13.
6) Checked for errors -- received "Great News! -- Your return has no errors" from TTD2020 (but it had lied about that before)
7) Resubmitted my CA State tax filing, which miraculously, on this third attempt was accepted.
I hope this post helps any other weary soul who is wrestling with the CA FTB Form 5085 in TurboTax.
