I ran into the same problem, I filed my 2018 taxes in April but didn't realize I could deduct the 529 contributions for Michigan until now. TurboTax doesn't make it very obvious. Can you tell me what forms to use in order to claim an additional deduction for contributing to 529 as an amendment? On the form I found, the only section I can find to enter is "voluntary contributions." Is this where I enter in the contribution amount for the 529 plan? Does anyone know if "all voluntary contributions" would be including 529 contributions? Thanks in advance.
