In general, charitable deductions are limited to 60% of AGI for cash contributions and 30% of AGI for contributions of appreciated assets, such as stock. But these are not additive. So if you contribute 30% of AGI with appreciated stock you can only deduct another 30% of AGI with cash. The cash deduction is taken first, then the appreciated asset deduction.
However, the cap is a little different if contributions are made to certain types of charities, called "50% limit organizations". In that case, after recognizing the 30% cash deduction you can only deduct appreciated stock up to the lesser of (1) 50% of AGI minus cash contributions or (2) 30% of AGI. So if your cash contributions were 30% of AGI, this leaves you with a cap of only 20% of AGI.
Bottom line, it is critical that TT treat your contributions correctly as to whether they are to "50% limit orgs". When I put dummy data into my 2024 return to it treats contributions to my donor advised fund as being to a "50% limit org" and limits my deduction accordingly. My research tells me that is incorrect, but I don't see any place in TT to override that designation.
