Michigan Pension Subtraction Disallowed

[MIGander4]

I prepared my 96 year old mother's taxes using Turbo Tax.  She just received a letter from the Michigan Department of Treasury disallowing her pension subtraction.  She receives the pension as the surviving spouse of my dad, as indicated by Code 4 on the 1099.  For years there has been no issue with the subtraction of this pension, but from reading the above responses, it seems that the problem is that my dad's identifying information was not included on her 2025 tax return.  What is the solution for this problem? Can I simply respond to the Notice of Adjustment I received from Michigan or do I need to amend her return?

[Bsch4477]

Follow the instructions on the letter.