I'm thinking this is not a good idea. Yes, you want to save taxes. But here are the rules:"Contributions to an Illinois 529 plan of up to $10,000 per year by an individual, and up to $20,000 per year by a married couple filing jointly, are deductible in computing Illinois taxable income. For a rollover contribution, only the principal portion is eligible for the deduction. Contribution deadline is December 31 postmark.""Effective January 1, 2007, rollovers from this plan to an out-of-state program are included in Illinois taxable income to the extent of prior Illinois deductions. Effective January 1, 2009, nonqualified distributions from this plan are included in Illinois taxable income to the extent of prior Illinois deductions."I could not find anything in the rules that says you can't invest and withdraw in the same year. But they are bound to catch you -- and likely to disallow the tax deduction. And even if you had a longer horizon, and wanted to roll to a different state plan (with lower fees or better performance) they are on the lookout per the second paragraph.Don't start playing tax games with your kids' college tuition! You may outsmart yourself. If your time horizon is truly short, then you can't expect to learn more than a money market rate of interest. And if you don't want this money to count against you because you are filing for FAFSA this year (money in a custodial account weights 7x more heavily against you in the financial aid formula), then spend it on a new computer or other legitimate expense for your child.