Here's a second way to cut your taxes long after the tax year has ended: fund your health-savings account (HSA) by April 15. Singles can make a deductible contribution of as much as $2,900; married couples, $5,800. HSAs are different from flexible-spending plans. In a flexible-spending plan (for health or dependent-child-care reimbursement), you make a pretax contribution but forfeit whatever you don't spend in a given year. With an HSA, you own the account, which typically is paired with a high-deductible health-insurance policy. Your contributions are tax deductible, and your account rolls over (and hopefully builds) each year. It can be drawn on at any time for out-of-pocket health-care expenses, and there are no income limits.