<p>Your child will have to file a tax return next spring if he or she earned over a certain amount.</p> By Kimberly Lankford, Contributing Editor September 3, 2009 My 17-year-old son worked as a lifeguard this summer at our local swimming pool. Does he need to file a tax return next April?It depends on how much he earned on the job and how much he earns from any other investments in 2009. Kids who are claimed as dependents on their parents' returns must file a tax return if they earn more than $5,700 from a job in 2009. If your son earned less than that, he still may be required to file a return if he earns more than $300 for the year from any investments in his name, such as from a bank account, mutual fund or custodial account. (Dependent children who don’t have jobs have to file if their investment income is more than $950 in 2009.) For more information about the tax-filing rules for children, as well as details about which forms to submit, see IRS Publication 929, Tax Rules for Children and Dependents. Even if your son isn't required to file a tax return, he might want to do so anyway to get back any income taxes that his employer withheld. He won't be able to get back any wages that were withheld for Social Security taxes, but the work he did counts toward his future Social Security eligibility. Advertisement And because he had a job, he can take advantage of a valuable tool to help him save for the future. Because your son has earned income -- regardless of whether he has to file a tax return -- he can open a Roth IRA, which can give him a huge head start on retirement savings. The maximum IRA investment in 2009 is $5,000 for anyone younger than 50 (it's $6,000 for people who are 50 or older), but he can't contribute more to the IRA than the amount of money he earned from a job during the year. If he earned $4,000 over the summer, for example, he can invest up to $4,000 in a Roth IRA. Few kids want to invest all their summer earnings in an account they won't tap for years, but you can give him the money to make the contribution or offer to match his contributions dollar for dollar (as long as the total contributions to his account for 2009 don't exceed the amount of money he earned for the year or $5,000, whichever is lower). And the money can grow substantially over the years: If the investments earn 6% per year (a conservative average over the long run), just that one $4,000 investment could grow to more than $73,000 by the time today's 17-year-old reaches age 67. He can withdraw the contributions tax- and penalty-free at any time, and he can take the earnings tax-free after age 59½. If he gets started in the saving habit and invests $4,000 every year until retirement, then he could amass an account worth about $1.3 million by the time he's 67, assuming 6% annual returns. See Roth Rules for Kids and Why You Need a Roth IRA for more information. Got a question? Ask Kim at email@example.com.