How to get turbotax to follow "Interest paid divided by interest rate" method from publication 936?

You would have to use the desktop version of TurboTax, where you can go directly to Schedule A and the Home Mortgage Interest Worksheet and make adjustments.

I am attempting to edit the Deductible Home Mortgage Interest Worksheet in the desktop version of TurboTax 2021 and it does not let me edit any of the values.  How can I edit so I can use the "Interest paid divided by interest rate method" of determining average mortgage balances?

@ThomasM125 

Here is how you can use the interest paid divided by interest rate method outlined in Publication 936:

1. In TurboTax Desktop, go to the Forms section of your return
2. Click on the Home Mortgage Interest Worksheet (Home Int Wkst)
3. Click on line 3, Outstanding Mortgage Principal, if you would like to use the interest paid divided by interest rate method you may, provided that you owned the home all 12 months and you paid monthly.
4. Click the Cross next to the entry to Add your supporting details
5. For your description, type in the formula that you are using to determine your outstanding mortgage balance. For example, 24500 interest paid / .03 interest. If your interest rate varied during the year, you must use the lowest interest rate for this method.
6. In the amount, type in the Outstanding Mortgage Principal determined by this method. In this example, that would be 816667.
7. That amount should automatically replace the original amount on Line 3 as reported on your 1098. 

@KyleG

I do not see any cross or way to change original Outstanding balance to the interest paid divided by interest rate method.. 

any further help would be greatly appreciated.

TurboTax does not provide for that alternative. 

However, you can manually perform that calculation and post it to your return. 

The method described by RaifH is posted directly in the FORMs mode of the CD/Desktop version.  This is not recommended because it will void the TurboTax accuracy guarantee.