I can not find line 8a on the 1098 form of the online version of Turbo Tax. Can anyone show me where to go to find this line?

I was able to find a solution in this post here. If copying from line 1 to line 2 does not resolve the issue, please feel free to reach back out via this forum. Otherwise, you may also contact customer care by following the steps here. 

actually, upon reading IRS publication 936 which says your mortgage interest deduction maybe limited depending on your loan balance and when your loan was pulled out. Anything before Dec XX 2017 (check exact dates in publication) has a loan balance of up to $1M and any mortgage interest is fully deductible if under that amount. If over $1M, there is a calculation sheet from publication 936 and the result calculated on line 15 is the amount you input to the 2nd line of Schedule A line 8A.

Anything after Dec XX 2017 (check exact dates in publication) has a loan balance of up to $750K and any mortgage interest is fully deductible if under that amount. If over $750K, there is a calculation sheet from publication 936 and the result calculated on line 15 is the amount you input to the 2nd line of Schedule A line 8A. Basically, I think its a pro-ration of your mortgage interest based on the proportion of your loan balance over $750K.