Calculating Lost Earnings Using the Tax Underpayment Rate (Posted January 15, 2005) Technical Tip 49: The following question and answer are from the DOL/EBSA website: What is the IRC §6621 rate and how do I find out what the rate was for the applicable time period? DOL Response: Section 6621 of the Internal Revenue Code establishes the rates for interest on tax overpayments and underpayments. The VFCP uses the underpayment rate as the rate of return that must be examined for determining lost earnings where it is not possible to ascertain the restoration of profits amounts. The Internal Revenue Service publishes the §6621(a)(2) rate quarterly. The rate announcements can be found on the internet. For context, see Technical Tip 48, "Earnings on Delinquent Contributions - Calculating Restoration of Profits." View all Tips © 2012 Reish Luftman Reicher & Cohen, a Professional Corporation Important notice: Answers are provided as general guidance on the subjects covered in the question and are not provided as legal advice to the questioner's situation. Any legal issues should be reviewed by your legal counsel to apply the law to the particular facts of your situation.