The Internal Revenue Service announced Tuesday that the 2014 tax-filing season will be delayed by up to two weeks as a result of the recent partial government shutdown.

The delay means taxpayers can start sending their 2013 tax returns in "no earlier than Jan. 28 and no later than Feb. 4," the IRS said.

The original start date was Jan. 21.

About 90 percent of all IRS operations were shuttered during the 16-day partial closure and the missing work came "during a peak period for preparing IRS systems for the 2014 filing system," according to the agency's statement.

The IRS said it is looking for ways to shorten the delay.