Can you explain what you are doing? SCH E rental, SCH C business, or SCH F farm income?
Depreciation of an asset starts on the date it was placed in service. If you did not take depreciation in the first tax year it was placed in service, and you haven't claimed depreciation for 2 or more tax years, then "adding" the depreciation you should have taken isn't an option, and fixing the issue isn't simple.
If this is a case of where you have been depreciating things correctly, but 2022 is the first year you are using TurboTax, the program will automatically figure the prior depreciation "for you" based on the numbers you provide. Typically, the program will be within $5 of correct, which is generally acceptable. If the prior depreciation figured by the program is way off, it's usually because of a data entry error, or the selection of the wrong MACRS asset type, or the use of an "alternative" but legal depreciation method for that asset type.
