Tax refund intercept to pay support arrears is authorized and mandated by 42 U.S.C. u00a7 664. The support obligation must be u201cpast due,u201d so if the obligor is reasonably current on whatever order is out thereu00b9 and there are no u201cassigned arrears,u201du00b2 there might not be an intercept.If a child support obligor is married filing jointly, the spouse will be notified of the withholding of the tax refund and given notice of what steps they can take to claim their own share. See subdivision (a)(3)(C).u00b3 If the spouse objects to the u201cintercept,u201d the IRS will make a ruling as to how much of the return is attributable to the obligor and how much to the spouse; the spouseu2019s share will be exempt and returned to them (though the process may take several months, a source of frustration to obligees and innocent spouses alike because refunds that are intercepted under this provision are put into a special account pending figuring all this out).The obligor should also have received notice of intent to withhold as part of this process. Id. subdivision (a)(3)(A). The obligor cannot object to the intercept; if the amount of claimed arrears is believed incorrect, this needs to be taken up with the court that issued the order.If the spouse does not claim the exemption, the IRS and the support agency will take the whole amount, with any amount in excess of the arrears to be refunded to the obligor eventually.Notes:u00b9 Per the IRS regulation at 26 C.F.R. u00a7 301.6402-5(b), u201cdelinquentu201d means three months past due.u00b2 u201cAssigned arrearsu201d are reimbursement to the state for amounts paid to the childu2019s household by way of a cash TANF grant, or certain Medicaid expenses or foster care expenses. These arrears belong to the Government, not the custodial parent. There is some discussion of the concept in this answer.u00b3 The statute provides as follows:(C) If the other person filing the joint return with the named individual owing the past-due support takes appropriate action to secure his or her proper share of a refund from which a withholding was made under paragraph (1) or (2), the Secretary of the Treasury shall pay such share to such other person. The Secretary of the Treasury shall deduct the amount of such payment from amounts subsequently payable to the State agency to which the amount originally withheld from such refund was paid.Emphasis added.