When adding mileage driven for volunteering - added 597 miles, state tax due goes up an additional $1000.00. Why this go up?

[Karis_F]

To clarify: what state tax return are you filing?

[skn]

State of Minnesota

[AmyC]

A couple of thoughts:

Most common, you lower your income a little bit and a big credit like MN Child and working families credit or MN education credit, is completely recalculated.

In MN, you can only deduct mileage if you itemize. I wonder if you were taking standard and switched to itemized at a lower rate.

Even if you accidentally entered the mileage as reimbursed, the numbers don't add up.

Take a loot at your tax return:

1. Compare your return (save a .pdf) both with and without the mileage. 
2. Double check standard or itemized
3. Look at the credits section