Most likely, there was an offset on your refund or possibly the IRS is aware of income you did not report. Usually something like back child support, unpaid qualified student loans or a W-2 you didn't receive because the issuer did not have your correct mailing address.
If there was an offset for any reason, then you can expect to get a letter from the IRS in 3-5 weeks providing you all the details, plus instructions on what to do if you disagree with the IRS.
