The interest rates paid on overpayments and underpayments remain the same in the fourth quarter of 2010 as they have been all year. Individuals will pay 4% on underpayments and receive interest of 4% on overpayments during this period. This rate has been in effect since April 1, 2009.
Source: Rev. Rul. 2010-21; 2010-39 IRB 1
A portion of earnings withheld by an employer or put into a retirement plan for distribution to the employee at a later date. If certain legal requirements are met, the deferred amount is not taxable until actually paid, for example, after retirement.