45 CFR § 32.6 - Withholding order.

(a) Unless the Secretary receives information that the Secretary determines justifies a delay or cancellation of a withholding order, the Secretary shall send, by first class mail, an SF–329A “Letter to Employer & Important Notice to Employer,” an SF–329B “Wage Garnishment Order,” an SF–329C “Wage Garnishment Worksheet,” and an SF–329D “Employer Certification,” to the debtor's employer within 30 days after the debtor fails to make a timely request for a hearing, i.e., within 15 business days after mailing the notice required under this part, or, if the timely request for a hearing is made by the debtor, within 30 days after a final decision is made by the Secretary to proceed with garnishment.

(b) The Secretary shall keep a copy of the dated letter to the employer and a copy of the wage garnishment order. The certificate of service may be retained electronically so long as the manner of retention is sufficient for evidentiary purposes.