The IRS is predicting a delay in the start of the tax filing season by up to two weeks from January 21 to as long as February 4. They are testing new procedures to detect identity theft and help prevent refund fraud and since they were on furlough for two weeks it sets back the testing two weeks. You don't think it could be that they are pissed at Congress for the shutdown do you? In December, the IRS will announce the official starting date.
In addition to the delay in the start date of 2013 tax filing season, the IRS is saying it will not issue refunds as quickly as in years past because of the anti-identity-theft controls it's implementing. The IRS has not announced about how much longer it will take to get a refund.
If you mailed any correspondence to the IRS during the government shutdown, don't hold your breath. The IRS Service Center was swamped, receiving an estimated 400,000 pieces of correspondence during the furlough, many of which were unopened. It will be quite a while before the IRS gets caught up. So anyone that sent in documentation in the last month to the IRS should not expect any resolution soon.
Between budget cuts and the furlough, customer service has taken a big hit at the IRS. None of us mind if they don't have time to do as many audits, but the phone hold times are the worst I have seen in my 21 years of dealing with the IRS and it's taking a very long time to get issues resolved with the IRS.