45 CFR § 31.5 - Notice.
(a) Requirements. If not previously included in the initial demand letter provided under section 30.11, at least 60 days before referring a debt for tax refund offset, the Secretary shall mail, by first class mail to the debtor's last known address, written notice informing the debtor of:
(1) The nature and amount of the debt;
(2) The determination that the debt is past-due and legally enforceable, and unless paid within 60 days after the date of the notice, the Secretary intends to enforce collection by referring the debt the Department of the Treasury for tax refund offset; and
(3) The debtor's rights to:
(i) Inspect and copy Department records relating to the debt;
(ii) Enter into written agreement to repay the amount of the debt;
(b) The Secretary will retain evidence of service indicating the date of mailing of the notice. The notice may be retained electronically so long as the manner of retention is sufficient for evidentiary purposes