I did my 2023 AZ taxes via turbotax. Today when doing my 2024 AZ taxes TT says I own an underpayment penalty. Why? I thought TT guaranteed it's calculations.

[ThomasM125]

The underpayment penalty is from not paying in your taxes on a timely basis. You are required to pay in roughly one quarter of your tax liability on a quarterly basis. If you end up owing taxes when you file your return or fail to pay in the proper amount quarterly based on your tax liability from the previous year, you may be penalized for underpayment of tax.