Consider a divorced individual who earns $26,000, has two children, and pays $4800 in child care expenses, $2000 in mortgage interest payments, and $4500 in medical expenses. Medical expenses in excess of 7.5 percent of one's income are deductible. When the individual's income is $26,000, he or she gets a 22 percent child care expense credit; when the income is $28,001, the credit is only 20 percent. The individual's base marginal tax rate is 15 percent. What is the actual marginal tax rate?