Note: You must complete a separate Form 3911 for each refund for which you are requesting information. Use Form 843 to claim a refund or request an abatement of certain taxes, interest, penalties, fees, and additions to tax.Check the box below that indicates your reason for filing Form 843. Tax. Abatement or refund of tax other than income, estate, or gift tax. The primary letter we use to request information about a return is Form DTF948 or DTF948O, Request for Information (RFI). The IRS sends out letters 5071C or 4883C that require taxpayers to verify identity before the IRS will continue processing a tax return. Internal Revenue Service (IRS) website, IRS Forms and Publications, Refund Status, IRS Withholding Calculator, Foreign Account Tax Compliance Act. Joy Krowski says she never thought she'd be so happy to get something in the mail from the IRS. "I'm so glad I got this letter," Krowski said. The refund process generally takes six to eight weeks to complete, depending on the time of year the refund is requested.