Fix for broken (as usual) Ded Home Mort limited mortgage interest calculation

[jgackson]

Depending when a home was purchased, you can only deduct interest on the first $750,000 or $1-million of mortgage principal. If your mortgage is bigger, the Ded Home Mort worksheet form is supposed to calculate the limited amount, drawing on the step-by-step questions that feed the Home Int Wkst form. As of Jan 28, it fails.

Specifically, the amounts from Home Int Wkst lines 3 and 6 are supposed to feed the "Beginning of year balance" and "Ending balance" lines in the appropriate panel of Ded Home Mort (which panel applies depends on the original mortgage date).

However, at least for the  1987-2017 panel (we bought in May 2017), the "Beginning of year balance" is blank even though the correct amount appears in Hom Int Wkst line 3. (The ending balance transfers correctly.) As a result, Ded Home Mort calculates that there is no deductible mortgage interest.

To get around this error (which has appeared, among other errors, in earlier years), the simplest fix is to override the the "Beginning of year balance" entry and type in (or copy-paste, although that's not working for me) the amount from Home Int Wkst line 3. Once that's done Home Ded Mort calculates the correct interest deduction, and that flows properly back to Schedule A.

With luck this will get fixed before filing time arrives, although in past years that's not always happened.

[user17703809885]

Having the exact same issue myself, and hadn't had this issue with last year's version of TT Deluxe (which is odd given that our mortgage situation hasn't changed).  Have already gone in to delete the 1098's twice and then re-entered all data, yet still got the same "no mortgage interest is deductibe" result.  I managed to override the values that didn't transfer to the M.I.D. WS as they should have, but would prefer TT fix this issue sooner-than-later to have more confidence in the accuracy of my calculations prior to filing.

[jgackson]

As I recall the problem was there last year, but got corrected at some point. If so, Intuit apparently went back to the old version, with the bug, this year. Like you I've tried everything I could think of--deleting forms and starting 1098 entry over, fudging mortgage origination date, etc--but the beginning balance entry in the middle (pre-Dec 2017) panel remains stubbornly blank unless overridden and entered manually.

[jgackson]

It's still broken as of 9 February 2026--I deleted the 1098 in Step-by-Step, then deleted the associated worksheets and Ded Home Mort in Forms, then re-entered the 1098 data, and once again the middle panel on Ded Home Mort failed to populate and I had no mortgage-interest deduction. Then I overrode "beginning of year" and entered the amount that should have transferred from the 1098 worksheet, and the deduction calculated correctly.

[jgackson]

Still broken as of the 3/18/2026 TT updates. Fix still works (overriding the starting balance in the appropriate Ded Home Mort panel.

[CatinaT1]

The updates come out overnight on Thursdays, generally. Have you tried it today? 

If you are using desktop software you may need to do a manual update. Try clearing your Cache and Cookies and then try this link instructions.

If you are using the online software, Clear Cache and Cookies. 

[jgackson]

There were updates yesterday (Thursday) morning, which were installed but didn't fix the problem.

There were no new updates today.

So the problem remains unsolved: At least for those of us eligible for the special higher mortgage-interest limit (that is, whose original loan was before the end of 2017), Ded Home Mort fails to copy a key piece of data from the 1098 worksheet. That's true regardless of whether the 1098 was uploaded from the bank or entered by hand (I tried both). Fixing the "starting balance" field by override causes everything else to work correctly; not doing that causes TT to make all the mortgage interest nondeductible.