31 C.F.R. § 285.8
(a) Definitions. For purposes of this section:
Debt means past-due, legally enforceable State income tax obligation or unemployment compensation debt unless otherwise indicated.
Debtor means a person who owes a debt.
Fiscal Service means the Bureau of the Fiscal Service, a bureau of the Department of the Treasury.
IRS means the Internal Revenue Service, a bureau of the Department of the Treasury.
Past-due, legally enforceable State income tax obligation means a debt which resulted from:
State means the several States of the United States. The term “State” also includes the District of Columbia, American Samoa, Guam, the United States Virgin Islands, the Commonwealth of the Northern Mariana Islands, and the Commonwealth of Puerto Rico.
State income tax obligation means State income tax obligations as determined under State law. For purposes of this section, State income tax obligation includes any local income tax administered by the chief tax administration agency of the State.
Tax refund offset means withholding or reducing a tax refund overpayment by an amount necessary to satisfy a debt owed by the payee(s).
Tax refund payment means any overpayment of Federal taxes to be refunded to the person making the overpayment after the IRS makes the appropriate credits as provided in 26 U.S.C. 6402(a) and 26 CFR 6402-3(a)(6)(i) for any liabilities for any Federal tax on the part of the person who made the overpayment.
Unemployment compensation debt has the same meaning as the term “covered unemployment debt” as defined in 26 U.S.C. 6402(f)(4), and means—
(b) General rule.
(3)
(e) Post-offset notice.
(1) When an offset occurs, Fiscal Service shall notify the debtor in writing of:
(k) Social Security numbers. Fiscal Service will ensure that an individual's Social Security number will not be visible on the outside of any package it sends by mail. In addition, Fiscal Service generally will redact or partially redact Social Security numbers in documents it sends by mail; however, to administer the tax refund offset program, Fiscal Service (and other disbursing officials) may include Social Security numbers in mailed documents, including, for example:
[64 FR 71231, Dec. 20, 1999, as amended at 74 FR 27433, June 10, 2009; 76 FR 5071, Jan. 28, 2011; 87 FR 50248, Aug. 16, 2022]