Why doesn't the interest listed on my 1098 match the year to date interest on my December mortgage statement?

only your bank can't explain.  we have no access to their records.  A possibility is you're looking at the interest paid from the date the loan was taken out, the 1098 would only reflect 2020 interest paid.   another possibility is the statement includes interest that was to be paid in December but your check arrived in January.  These are only guess. when you call ask to speak to someone higher up at the bank. if they can't tell you ask them if you should inform your local newspapers about the problem the bank is having.  or report the bank to your local newspaper. 

Thanks for the reply. I guess I was wondering if there was a general reason why the interest reported on the 1098 would be different than the interest actually paid. I spent a couple of hours on the phone with my bank today to try to find someone to explain why this might be, and I couldn't get anyone who even knew how to correct a 1098. 

So I guess the next question is, if I definitely paid more interest than is being reported on my 1098, and can prove that I did, I should deduct the actual interest I paid, right?

You can report the actual interest you paid even though the amount reported on your form 1098 is different. It is probably a timing difference, so you may have to reverse the adjustment next year though.