Below is a link to a page on the IRS website with information for taxpayers:
What to Expect for Refunds in 2013
http://www.irs.gov/Refunds/What-to-Expect-for-Refunds-in-2013
IRS also provides a PDF with 2013 refund information for tax preparers at the link below.
2013 IRS Refund Information Guidelines for the Tax Preparation Community
http://www.irs.gov/pub/irs-pdf/p2043en.pdf