Alternative Minimum Tax is triggered in certain situations and TurboTax automatically performs the calculations based on the entries you make in the software. It can be best described as follows:
"The Alternative Minimum Tax is a separate tax calculation determined in parallel with an individual’s regular income tax calculations. The AMT takes out various tax preferential items that an individual may receive, which lowers his taxable income. The AMT was designed to ensure that high-income earners do not pay little-to-no tax but instead pay a minimum".
More information from CRA can be found here;
https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/tax-re...
