Here is the link for the TurboTax audit support center. Even if you didn't purchase Audit Defense, this may help.

I would also recommend calling the number on your notice and asking for more information on how they reached that determination. It's a good idea to have the state return in question printed up or on your computer when you call in case you need to refer to it. For your reference, here is another number for the Missouri Department of Revenue: 573-751-3505

I Efiled my state tax. I need to pay the taxes. Do I just mail in the payment voucher and a check?

You will need to contact your state for the address to mail your payment. Please refer to the page below to contact your state.

How do I contact my state Department of Revenue?