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Software Developer Website for Substitute Forms and Electronic Filing
Software Developer Website for Substitute Forms and Electronic Filing
Michigan Treasury Updates
Treasury is now accepting TY26/WH27 Letters of Intent (Form 4430). Initial Letters of Intent (Form 4430) must be submitted by November 15, 2026 to be granted access to participate in Michigan's e-file and substitute forms programs.
NOTE: If your business/organization supports ONLY Personal Property Tax forms, you do NOT need to submit Form 4430. The most recent version of the Personal Property Tax forms are on Treasury’s Web site.
Once your company’s 4430 is processed, your company will receive an e-mail from Support@taxadmin.org which will provide you access to the approved folder(s) with the State Exchange System site.
Michigan Department of Treasury will post all e-file and form information to the State Exchange Site.
Software developers should reference the Substitute Forms Submissions Manual for guidelines on submitting substitute forms. Software developers are not to submit forms for testing until forms are posted as “Final Drafts.”
Contact Information
E-mail: MIFormsEfile@michigan.gov