I think that the math problem is with TurboTax.
This thread about 2020 discusses the issue as well:
https://ttlc.intuit.com/community/tax-credits-deductions/discussion/problem-that-turbotax-does-not-b...
TurboTax reports the Qualified Contribution Elected as the difference between the total charitable deductions and 60% of the AGI. The problem is that results in a lower deduction as calculated by the IRS.
As an example, let's try:
100K$ AGI
35K$ qualified cash
15K$ non-qualified cash
20K$ non-cash
50K$ total cash
The TurboTax Charitable Deductions Limits Worksheet follows the pub 526 worksheet and calculates the non-qualified cash as 15K$. This is correct. However, TurboTax only shows 10K$ on the dotted line on Schedule A line 11 instead of 35K$. The IRS does not see the worksheet - only the dotted line amount.
So, the IRS thinks that 40K$ is non-qualified (50K$ - 10K$) instead of 35K$. This propagates into later calculations and reduces the total deductions to 60K$ instead of 70K$ based on IRS rules. But TurboTax reports a 70K$ deduction. So, the IRS computer sees an error in the calculations.
I ran a test return on a trial version of TaxAct and they correctly report the full 35K$ qualified contribution amount on the dotted line for line 11.
When I use the IRS rules based on the numbers on my return, I get a different total deduction than the IRS. But I suspect that since the IRS sees an inconsistency in the reported deductions, it just limits the total to 60% of AGI.
I think I need to submit a modified version of Schedule A showing the total qualified contributions on the dotted line of line 11 instead of the reduced amount calculated by TurboTax.
