In 2017, Tomas, a single taxpayer, had $ $3,750 in state tax withheld from his paycheck. He properly deducted that amount on his 2017 tax return as an itemized deduction that he qualified for, thus reducing his tax liability. After filing his 2017 tax return, Tomas discovered that he had overpaid his state tax by $417. He received his refund in July 2018. What must Tomas do with the $417 refund? Explain your answer.