First, I would hope that TurboTax does the computations for you once you put in the information.
Next, if you closed on your loan before 12/16/2017, or had a contract to close by 1/1/2018, then closed by 4/1/2018, then you can deduct the $1 million limit. This is why the 1098 includes origination date.
If after 12/16/2017, then yes the 750k limit applies, AND if Turbo Tax doesn't do the calculations for you, then you can go to https://www.irs.gov/publications/p936 and go to the Table 1 and Table 2 to get the calculation correct.
[ how I interpret it (Check my numbers), if closed AFTER 12/16/2017: 375,000(half) / $1,068,518= .351 then .351 * 22,430=7,872.93 or 7873]
