About 7,100 Hawaii taxpayers who didn’t file returns in 2011 could have federal refunds totaling $6.8 million waiting for them, and time is running out to claim the money.

"People could be missing out on a substantial refund, especially students or part-time workers," IRS Commissioner John Koskinen said in a news release. "Some people may not have filed because they didn’t make much money, but they may still be entitled to a refund."

The IRS estimates that half of the potential refunds exceed $742. The deadline to file those overdue 2011 returns is Wednesday, Tax Day. There is no penalty for filing a late return that qualifies for a refund.

In some cases, people who thought they didn’t earn enough to have to file a tax return file could get cash back through tax credits, said IRS spokesman David Tucker, based in Seattle.

"They don’t realize they may be eligible for a tax credit which would actually provide them with a refund," Tucker said Wednesday. "The earned-income tax credit is one example. It is a refundable credit, which means that that money comes back to you as a refund and puts money back in your pocket."

The EITC is targeted toward people with low or moderate incomes, up to $40,964 in 2011 for married couples who file jointly and have two children.

"It’s money due to them, and we want to make sure it gets to them as soon as possible," Tucker said. "If they don’t file by April 15, then they no longer can claim that money."

Three years after the filing date, the money that would have been refunded to the taxpayer becomes the property of the U.S. Treasury.

Tax forms are available at irs.gov under "Forms and Pubs" or by calling 800-829-3676.