Yes, the new deduction for seniors is in addition to the standard deduction.
There is no formula for calculating AGI (Adjusted Gross Income). AGI is your total income of any type, minus adjustments. (Adjustments are from Part II of Schedule 1.) Total income and AGI include the taxable portion of Social Security benefits. The taxable portion of Social Security benefits could be anywhere from zero to 85% of the benefits, depending on your other income and other factors. Many other factors could affect your AGI, depending on the types of income that you have. Basically the only way to calculate AGI is to prepare the income and adjustments sections of the tax return. As I said, there is no formula.
This answer has been verified for accuracy by an Intuit expert employee
