Q. How does contributing to an IRA impact on the need to file a teenager's return?
A. Simple answer: he still does not need to file a tax return.
Since the child does not need an IRA deduction (his taxable income is already 0), you most likely want to invest in a Roth IRA. A contribution to a Roth IRA does not need to be reported on a tax return. A Traditional non-deductible IRA contribution does need to be filed, but can be file on a stand alone form 8606 (does not have to be part of a whole tax return).
A dependent is not eligible for the Retirement Savings Contribution Credit. So, he does not need to file for that.
