31 U.S. Code § 3720D - Garnishment
Notwithstanding any provision of State law, the head of an executive, judicial, or legislative agency that administers a program that gives rise to a delinquent nontax debt owed to the United States by an individual may in accordance with this section garnish the disposable pay of the individual to collect the amount owed, if the individual is not currently making required repayment in accordance with any agreement between the agency head and the individual.
(b) In carrying out any garnishment of disposable pay of an individual under subsection (a), the head of an executive, judicial, or legislative agency shall comply with the following requirements:
The amount deducted under this section for any pay period may not exceed 15 percent of disposable pay, except that a greater percentage may be deducted with the written consent of the individual.
(2) The individual shall be provided written notice, sent by mail to the individual’s last known address, a minimum of 30 days prior to the initiation of proceedings, from the head of the executive, judicial, or legislative agency, informing the individual of—
the intention of the agency to initiate proceedings to collect the debt through deductions from pay; and
The individual shall be provided an opportunity to inspect and copy records relating to the debt.
The individual shall be provided an opportunity to enter into a written agreement with the executive, judicial, or legislative agency, under terms agreeable to the head of the agency, to establish a schedule for repayment of the debt.
(5) The individual shall be provided an opportunity for a hearing in accordance with subsection (c) on the determination of the head of the executive, judicial, or legislative agency concerning—
A hearing under subsection (b)(5) shall be provided prior to issuance of a garnishment order if the individual, on or before the 15th day following the mailing of the notice described in subsection (b)(2), and in accordance with such procedures as the head of the executive, judicial, or legislative agency may prescribe, files a petition requesting such a hearing.
If the individual does not file a petition requesting a hearing prior to such date, the head of the agency shall provide the individual a hearing under subsection (a)(5)  upon request, but such hearing need not be provided prior to issuance of a garnishment order.
The notice to the employer of the withholding order shall contain only such information as may be necessary for the employer to comply with the withholding order.
An employer may not discharge from employment, refuse to employ, or take disciplinary action against an individual subject to wage withholding in accordance with this section by reason of the fact that the individual’s wages have been subject to garnishment under this section, and such individual may sue in a State or Federal court of competent jurisdiction any employer who takes such action.
(1) The employer of an individual—
shall pay to the head of an executive, judicial, or legislative agency as directed in a withholding order issued in an action under this section with respect to the individual, and
The head of an executive, judicial, or legislative agency may sue an employer in a State or Federal court of competent jurisdiction to recover amounts for which the employer is liable under paragraph (1)(B).
For the purpose of this section, the term “disposable pay” means that part of the compensation of any individual from an employer remaining after the deduction of any amounts required by any other law to be withheld.
 So in original. Probably should be subsection “(b)(5)”.