Was it a Roth 401(k) or a 401(k). "Regular" 401(k) contributions are already NOT TAXED, so your W2 Box1 income reflects the deduction. Roth is not pretax.
You can never deduct your 401k contributions on your tax return, as there's simply no place to do so.
401k contributions go in box 12 of your W2, with a Code D. Please look at the hard copy of your W2 to see if its there.
If your income is low enough, the code D amount could give you a small Saver's Credit on your return. If you don't have a code D, report back to your employer for a corrected W2.
401(k) contributions already lower your taxable wages, so they cannot be double-deducted on your tax return.
Thanks for your response! So I just have a code DD in box 12, no code D. Should everyone who contributes to their 401K (Roth or Regular) have a code D on their W2?
Well, everyone who has regular is D. Roth is AA. Do your box 1 wages appear to reflect the deferral, if its401(K). Roth is not tax deferred. Do you have a 401K for sure?
I think I do, on my paycheck it's listed as "Optional Retirement Program EE" and I know it's managed through TIAA. I'm not sure if my box 1 wages reflect the deferral - what would be the easiest way to tell?
Well, TIAA is not a 401k. You contributions also might not be pretax. The best way is to look at your paystub or ask someone at work. Either way, its not really a part of your tax return. But you should, of course, know the deal.