29 CFR § 102.174 - Debtor notification.
(1) The debt is past-due;
(2) Unless the debt is repaid or a satisfactory repayment agreement is established within 60 days thereafter, the debt will be referred to the IRS for offset from any overpayment of tax remaining after taxpayer liabilities of greater priority have been satisfied; and
(3) The debtor will have a minimum of 60 days from the date of notification to present evidence that all or part of the debt is not past due or legally enforceable, and the Agency will consider this evidence in a review of its determination that the debt is past due and legally enforceable. The debtor will be advised where and to whom evidence is to be submitted.
(c) The Agency will make a reasonable attempt to notify the debtor by using the most recent address information available to the Agency or obtained from the IRS, unless written notification to the Agency is received from the debtor stating that notices from the Agency are to be sent to a different address.
(d) The notification required by paragraph (b) of this section and sent to the address specified in paragraph (c) of this section may, at the option of the Agency, be incorporated into demand letters required by paragraph (a) of this section.