If you have claimed "other deductions", "carrying charges", "exploration and development expenses (line 22400)" and/or "limited partnership income or loss (line 12200)", you have to complete this form to specify some Minimum Tax related amounts. TaxChopper will do the calculations to see if you can pay the minimum tax.
Even if you don't have any of the amounts listed on this form (most people don't), you still need to confirm this to let TaxChopper know you have checked the form. Your confirmation message will be sent to CRA with your return. If you don't confirm, the message remains.