@hbl3973 - thanks for the follow-up. It looks like those steps (in the Federal Estimated and Other Taxes Paid section) are exactly the ones I executed. That's what caused the error in the first place, because the program doesn't ask what that tax payment pertains to, it just labels it an "other" estimated tax.
The problem is that the connection between Federal and State sections is one-way, feeding forward data but not taking into account where that data needs to go. If I were managing the software development, I'd have them create the proper queries to connect the two, so the payment is properly attributed. Since the software doesn't do that, it results in a duplicate payment: first in the estimated state tax payment section, and then in CA Form 593, which it knows to ask about because I'm reporting a home sale in CA! It should also know that when I'm reporting the home sale in the Federal section.
CA 5805 doesn't apply here, at least not to me. I actually overpaid the CA tax.
