What is the interest rate on overdue admended tax returns?

I filed my taxes this year and had to amend one of my w2. It has been 14 weeks and 2 days since they received it. I called the IRS and they said that it was delayed and they where going to start paying interest after the 12th week. I'm wondering what the interest rate will be because they never told us. Will they pay us based on each day it's late or weekly that it's late daily???|||The IRS interest rate is currently 5%. It's taxable interest and frankly won't add up to very much.|||don't go crazy and spending money you think you be getting as interest. It will probably on be a few dollars.