W2 Box 12 has code AA. Do I report the amount for AA in the Retirement and Investment section? Do I list the amount as a Roth contribution?

[DoninGA]

No.  Those are contributions to a Roth 401(k) and are not entered anywhere else on a tax return.

[RaifH]

No, you do not need to list this as a Roth contribution. This is a contribution to a Roth 401(k), not a Roth IRA. While a contribution to a Roth 401(k) does not lower your taxable income like a contribution to a traditional 401(k) would, the earnings grow tax-free and qualified distributions from this account are tax-free. In addition, your contribution may qualify you for the retirement contribution credit if you meet the criteria.