I found the answer on the Maine DOR FAQ: https://www.maine.gov/revenue/faq/income_faq.html#faq1040_10
In the answer, it states:
- Check the filing status box for Single. Do not check the box for Married filing separately, Married filing jointly, or Head of household.
Even though one typically checks the Married Filing Separately box, Maine requires you to check Single filing status. So TurboTax creates the correct forms and correct filing status for those filing federal as Married Filing Jointly, and deriving the Maine Married Filing Separately from it.
