Advancing Youth Enrollment Act This bill amends the Internal Revenue Code to increase the premium assistance tax credit for taxpayers with household members between the ages of 18-34. (The credit is available to eligible individuals and families to subsidize the purchase of health insurance on an exchange established under the Patient Protection and Affordable Care Act.) The bill allows an increased tax credit for the purchase of health insurance by reducing the maximum percentage of income that taxpayers under age 31 must pay for coverage by 2.5%, with reductions of .5% for each year for ages 31-34.