The Roth 401k is a 401k where you "designate" your contribution as "Roth" meaning it is already taxed, and other considerations I won't list here. It is a type of employer plan.

The same Roth IRA contribution rules apply to a person who participates in a Roth 401k as to any other person. The Roth 401k contributions do not replace or limit the Roth IRA contributions.

In particular, if your income is above $110K for single, or above $160K for married filing jointly, then you cannot contribute to a Roth IRA.

If you want to contribute to a traditional IRA, then you follow the rules for an "active participant" in an employer plan. In particular, if your income is above $50K for single, or $70K if married filing jointly, then you cannot make a deductible contribution to a traditional IRA.

The short answer is yes, you can still contribute to individual Roth and Traditional IRAs. However, when you are covered by your employers retirement plan there are limits to how much you can contribute. The limite is dependent on your modified adjusted gross income and your age.

See IRS document Publication 590, page 14 for explanation. http://www.irs.gov/pub/irs-pdf/p590.pdf

If you have a spouse who makes less or no income, you may also save money (and reduce your taxes) by opening an IRA for your spouse.

Best wishes.