Does a code DD in box 12 affect overall agi. I.E. box 1 says 21,437 and box 12 says 17,324, does this lower agi to 4,113?

[IreneS]

No.  Box 12 amounts with the code DD signify the total cost of what you and your employer paid for your employer-sponsored health coverage plan.

Code DD amounts are for informational purposes only – they won't affect the numbers in your tax return.

Nevertheless, you should enter the Code DD and the amount of your employer-sponsored health coverage plan if you see it on your W-2.