Q. My question is do I have to file my MI with the total $19,000 plus, $500 or all together $ 19,500?
A. You enter the two W-2s separately.
You say " My other employer held taxes for OH". If the withholding was only in box 19, of your W-2, that is city income tax, not Ohio state income tax. You cannot get city tax refunded. City tax is not covered by the MI-OH reciprocal agreement.
Michigan will give you credit, on the MI state return for OH city tax withheld, but you have to attach a copy of the city return. So, even though the Ohio city does not require you to file a return, you have to file one to get the MI credit, even though there will be no tax due or refunded from the Ohio city.