AMT gives even tax professionals a headache at times. It is not easy to understand.
The software is changing your depreciation because for AMT purposes, you generally must depreciate (deduct) business assets over a longer period of time than you can for regular tax purposes. This creates a difference between regular tax depreciation and AMT depreciation. The adjustment is not a tax you pay.
The IRS requires that you calculate your tax in 2 different ways, you need to calculate your regular tax and you need to calculate you income and deductions for AMT (alternative minimum tax). You end up paying which ever one is higher. The good news is that the new tax law, Tax Cuts and Jobs Act ,made changes to the AMT tax rules so you are less likely this year to be subject to AMT rules.
Line 34 on the 6251 will tell you if you have to pay any extra tax due to AMT. TurboTax will calculate all of this for you.
Please see below for the TurboTax FAQ ( really great guide) regarding AMT:
https://turbotax.intuit.com/tax-tips/irs-tax-return/alternative-minimum-tax-common-questions/L50YotK...
