Hawai'i residents have failed to collect an estimated $11.1 million in tax refunds because they failed to submit a federal income tax return for 2005, the Internal Revenue Service said.

The IRS estimated there were probably 9,400 individuals who could collect an average of $639. The tax agency said to collect the money people will have to file a 2005 return no later than April 15, 2009.

The unclaimed refunds are among an estimated $1.3 billion nationwide. The IRS said some people may not have submitted returns because they had too little income to require filing even though they had taxes withheld from wages or made quarterly estimated payments.

Moreover, the tax agency said some people stand to lose even more if they are low-income workers who have not claimed the Earned Income Tax Credit by filing a return.