Unclaimed federal income tax refunds, totaling as much as $1.1 billion, are waiting to be claimed. The IRS says an estimated 1 million taxpayers, including students and part-time workers, didn’t file 2014 tax returns and are due refunds. They have until April 17 to file. That’s when the statute of limitations for 2014 ends. Those seeking 2014 refunds may have theirs held if they haven’t filed returns for 2015 and 2016. Refunds also will be applied to any amounts owed to the IRS or a state tax agency. There’s no penalty for filing late if you’re due a refund.