I've adjusted the mortgage interest to only show eligible home acquisition interest, but the summary page says I have about $12K of deductible interest.
Your tax deduction is $10,000 and your mortgage interest deduction is $12,000, so the total is less than the standard deduction for a married couple filing joint of $24,800.
If you are filing single, the standard deduction is $12,400.
Do you have any rental or self-employment income that is taking some of your mortgage interest deduction away?
The summary page says I have $12,000 of deductible interest, but I should have about $40,000 of deductible interest. I don’t know what could be lowering it.
I don’t have any rental income or self employment income.
$40,000 of interest indicates a pretty hefty loan balance.....unless you are talking about two homes.
High balance loans have interest limitations, though $12,000 seems too small, I'm guessing your loan amount is over the limits, & you likely can't get the full 40k for one home.
What was the balance on that loan on 1Jan of 2020 ?
Read : https://ttlc.intuit.com/community/credits-and-deductions/help/can-i-deduct-my-mortgage/01/25755
$40,000 in interest only? The principal part of your mortgage payment is not deductible.
The balance of the home acquisition debt as of 1/1/2020 was 811,000. The loan was originally taken out in 2005, but refinanced a couple times since then, most recently in 2020. Does that mean I can only deduct the interest on $750,000 of the debt?
I'm not a good source for that situation...I do see some references that if you are filing MFS, the amount you can deduct may be halved too in certain situations. I have no idea if TTX applies the limit properly or not.
There's a bunch of details in the 2019 Pub 936 (didn't find a 2020 version).
https://www.irs.gov/pub/irs-pdf/p936.pdf