My 401k provider has both my mailing addresss (MNI) and legal state of residence address (FL) . The withdrawal was taxed based on my mailing address. How do I get this corrected.

It is probably too late, as the withholdings are sent to the IRS and state (in this case, Minnesota) almost immediately and can only be recovered by filing a tax return.

How do I do this during tax filing? Is there a special form I have to file to get the taxes back?

How do I do this during tax filing? Is there a special form I have to file to get the taxes back?

Your distribution was not taxed. That only happens when you file your return. What happened was an amount was withhold towards your tax liability.

When you file your return, you just file for the corrected amounts. If you overpaid or withheld amounts were credited to the wrong state, you file a return for that state indicating non residency and apply for a full refund.

Scott has it correct. You will file as a non-resident of Minnesota and apply for the full refund of the withheld state taxes.