Revenue Ruling 2002-62 and SEPP Plans post 12/31/2002: The interest rate that may be used is any interest rate that is not more than 120 percent of the federal mid-term rate for either of the two months immediately preceding the month in which the distribution begins.
This very conservative approach can help assure that you will not prematurely deplete your retirement account. If you have a higher rate of return your account can actually grow even while taking your planned distributions. However, if your account suffers, your IRA account may end up shrinking faster than you planned.
The Applicable Federal Rates [AFR] are published monthly by the Treasury around the 22nd of each month. Included in the published rates is the 120% Mid-Term Rate.