Once the MCC (Mortgage Credit Certificate) and Mortgage Interest is entered into TurboTax at the full amounts the program will reduce the deductible mortgage interest by the amount of the non-refundable MCC.
The adjustments are automatic. It does not appear to matter which order you put them in. Either the Mortgage interest first or the MCC first as long as they are both entered.
Your mortgage interest amount would be reported on form 1098. If you did not receive a 1098, contact your mortgage lender for the amount of interest paid or look to your mortgage statement.
To navigate to the section for qualified mortgage credit certificate holders:
To claim this credit, you must have applied for it when you originally bought or refinanced your home.