How do I use the short method on underpayment of Estimated Income Tax? Turbo tax is using the regular method, numbers don't add up, causing state taxes to be rejected.

@AmeliesUncle, I believe, is familiar with MN.

You might want to contact Support in the interim.

What is the TurboTax phone number? (intuit.com)

I haven't encountered things not adding up correctly or not showing up, but in regards to your desire to use the Short Method, do you qualify?  In order to use the Short Method, one of the below needs to apply:

• You did not make any estimated tax payments (or your only payments were from Minnesota income tax withheld from your wages).
• You paid your 2021 estimated tax in four equal amounts on or before the due date of each installment.

If you need to use the Regular Method, that is not eligible to be e-filed.

@AmeliesUncle My taxes were rejected by MN because the numbers aren't correct on the M15. Do I need to correct it on paper and send that in to the state? Do I send just the M15 or do I need to print and send in all tax paperwork? 

The M15 is part of the tax return, so it needs to be mailed with the rest of your state tax return.

If you are sure that the information on it is incorrect, you may want to contact Customer Support.  However, in the event it is a program error, it won't be fixed anytime soon.  But as I mentioned before, if you are required to use the "Regular Method", that isn't eligible for e-file even if it is populated correctly.