There is not a list of unsupported state tax forms.
However, there is a list of the supported state tax forms.
See this TurboTax support FAQ for Michigan state forms supported in the personal editions - https://care-cdn.prodsupportsite.a.intuit.com/forms-availability/turbotax_mi_online_individual.html
See this TurboTax support FAQ for the Business Edition state forms supported - https://care-cdn.prodsupportsite.a.intuit.com/forms-availability/turbotaxbusiness_states.html
