(a) In general. (1) An employer who has overcollected or overpaid employee Federal Insurance Contributions Act (FICA) tax under section 3101 or employer FICA tax under section 3111, employee Railroad Retirement Tax (RRTA) tax under section 3201 or employer RRTA tax under section 3221, or income tax required under section 3402 to be withheld, and has repaid or reimbursed the amount of the overcollection of such tax to the employee, shall correct such error as provided in this section. However, this section only applies to overcollected or overpaid Additional Medicare Tax under section 3101(b)(2) or section 3201(a) if the employer has repaid or reimbursed the amount of the overcollection of such tax to the employee in the year in which the overcollection was made. Such correction may constitute an interest-free adjustment as provided in paragraph (b) or (c) of this section.

(2) Every correction under this section of an overpayment of tax shall be made on the form prescribed by the IRS that corresponds to the return being corrected. The form, filed in accordance with this section and the instructions, will constitute an adjusted return for the return period being corrected.

(3) Every adjusted return on which an overpayment is corrected pursuant to this section shall certify that the employer has repaid or reimbursed its employee, except where taxes were not withheld from the employee or where, after reasonable efforts, the employer cannot locate the employee. Every adjusted return shall designate the return period in which the error was ascertained and the return period being corrected, explain in detail the grounds and facts relied upon to support the correction, and set forth such other information as may be required by this section and § 31.6413(a)-1 and by the instructions relating to the adjusted return. Every adjusted return, filed by an employer, for overpayment of employee FICA tax under section 3101 or employee RRTA tax under section 3201 collected from an employee in a calendar year prior to the year in which the adjusted return is filed, must also certify that the employer has obtained the employee's written statement that the employee has not claimed refund or credit of the amount of the overcollection, or if so, such claim has been rejected, and that the employee will not claim refund or credit of the amount.

(4) For purposes of this section, an error is ascertained when the employer has sufficient knowledge of the error to be able to correct it.

(5) For provisions related to furnishing employee statements and corrected employee statements reporting wages and withheld taxes, see sections 6041 and 6051 and §§ 1.6041-2 and 31.6051-1. For provisions relating to filing information returns and corrected information returns reporting wages and withheld taxes, see sections 6041 and 6051 and §§ 1.6041-2 and 31.6051-2.

(b) Federal Insurance Contributions Act and Railroad Retirement Tax Act—(1) Overcollection ascertained before return is filed. If an employer collects more than the correct amount of employee FICA or RRTA tax from an employee, and if the employer ascertains the error before filing the return on which the employee tax with respect to such wages or compensation is required to be reported, and repays or reimburses the employee under § 31.6413(a)-1(a)(1), the employer shall not report on any return or pay to the IRS the amount of the overcollection. If the employer does not repay or reimburse the amount of the overcollection under § 31.6413(a)-1(a)(1) before filing the return, the employer must report the amount of the overcollection on the return. However, the payment of the overcollection may subsequently be treated as an overpayment error ascertained after the return is filed for purposes of paragraph (b)(2) of this section.

(2) Error ascertained after return is filed—(i) Employee tax. If an employer files a return for a return period on which FICA tax or RRTA tax is required to be reported and reports on the return more than the correct amount of employee FICA or RRTA tax, and if the employer ascertains the error after filing the return, and repays or reimburses the employee the amount of the overcollection of employee tax, as provided in § 31.6413(a)-1(a)(2), the employer may correct the error through an interest-free adjustment as provided in this section. The employer shall adjust the overpayment of tax by reporting the overpayment on an adjusted return for the return period in which the wages or compensation was paid, accompanied by a detailed explanation of the amount being reported on the adjusted return as required by paragraph (a)(3) of this section. However, for purposes of Additional Medicare Tax under section 3101(b)(2) or section 3201(a), if the amount of the overcollection is not repaid or reimbursed to the employee under § 31.6413(a)-1(a)(2)(ii), there is no overpayment to be adjusted under this section and the employer may only adjust an overpayment of such tax attributable to an administrative error, that is, an error involving the inaccurate reporting of the amount withheld, pursuant to this section. Except as provided in paragraph (d) of this section, the reporting of the overpayment on an adjusted return constitutes an adjustment within the meaning of this section only if the adjusted return is filed before the expiration of the period of limitations on credit or refund. The employer shall take the adjusted amount as a credit towards payment of employment tax liabilities for the return period in which the adjusted return is filed unless the IRS notifies the employer that the adjustment is not permitted under paragraph (d) of this section.

(ii) Employer tax. If an employer files a return for a return period on which FICA or RRTA tax is required to be reported and reports on the return more than the correct amount of employer FICA or RRTA tax, and if the employer ascertains the error after filing the return, the employer may correct the error through an interest-free adjustment as provided in this section. The employer must first repay or reimburse the employee the amount of any overcollection of employee tax, if any, as required by § 31.6413(a)-1(a)(2), before making the adjustment for the employer tax. The employer shall adjust the overpayment of tax by reporting the overpayment on an adjusted return for the return period in which the wages or compensation was paid, accompanied by a detailed explanation of the amount being reported on the adjusted return as required by paragraph (a)(3) of this section. Except as provided in paragraph (d) of this section, the reporting of the overpayment on an adjusted return constitutes an adjustment within the meaning of this section only if the adjusted return is filed before the expiration of the period of limitations on credit or refund. The employer shall take the adjusted amount as a credit towards payment of employment tax liabilities for the return period in which the adjusted return is filed unless the IRS notifies the employer that the adjustment is not permitted under paragraph (d) of this section.

(c) Income tax withheld from wages—(1) Overcollection ascertained before return is filed. If an employer collects more than the correct amount of income tax required to be withheld from wages, and if the employer ascertains the error before filing the return on which the tax is required to be reported, and repays or reimburses the employee under § 31.6413(a)-1(b)(1), the employer shall not report on any return or pay to the IRS the amount of the overcollection. If the employer does not repay or reimburse the amount of the overcollection under § 31.6413(a)-1(b)(1) before filing the return, the employer must report the amount of the overcollection on the return. However, the reporting and payment of the overcollection may subsequently be treated as an overpayment error ascertained after the return is filed for purposes of paragraph (c)(2) of this section.

(2) Error ascertained after return is filed. If an employer files a return for a return period on which income tax required to be withheld from wages is required to be reported and reports on the return more than the correct amount of income tax required to be withheld, and if the employer ascertains the error after filing the return, and repays or reimburses the employee in the amount of the overcollection as provided in § 31.6413(a)-1(b)(2), the employer may correct the error through an interest-free adjustment as provided in this section. The employer shall adjust the overpayment of tax by reporting the overpayment on an adjusted return for the return period in which the wages were paid, accompanied by a detailed explanation of the amount being reported on the adjusted return as required in paragraph (a)(3) of this section. Except as provided in paragraph (d) of this section, the reporting of the overpayment on an adjusted return constitutes an adjustment within the meaning of this section. If the amount of the overcollection is not repaid or reimbursed to the employee under § 31.6413(a)-1(b)(2), there is no overpayment to be adjusted under this section. However, the employer may adjust an overpayment of tax attributable to an administrative error, that is, an error involving the inaccurate reporting of the amount withheld, pursuant to this section. The employer shall take the adjusted amount as a credit towards payment of employment tax liabilities for the return period in which the adjusted return is filed unless the IRS notifies the employer that the adjustment is not permitted under paragraph (d) of this section.

(d) Adjustments not permitted—(1) In general. If an adjustment cannot be made, a claim for refund or credit may be filed in accordance with § 31.6402(a)-2 or § 31.6414-1.

(2) 90-day exception. No adjustment in respect of an overpayment may be made if the overpayment relates to a return period for which the period of limitations on credit or refund of such overpayment will expire within 90 days of filing the adjusted return.

(3) No adjustment after claim for refund filed. No adjustment in respect of an overpayment may be made after the filing of a claim for credit or refund of such overpayment under § 31.6402(a)-2.

(4) No adjustment after IRS notification. No adjustment may be made upon notification by the IRS that the adjustment is not permitted.

(e) Effective/applicability date. Paragraphs (a) and (b) of this section apply to adjusted returns filed on or after November 29, 2013.