hearing officer after both parties argued that the indemnity agreement made Chino the real party in interest with regard to Teco’s protest of the assessment of gross receipts tax.
{12} We agree with the hearing officer that Chino is the real party in interest because Chino has indemnified Teco and is in a position to discharge Teco from liability. See L.R. Property Management, Inc. v. Grebe, 96 N.M. 22, 23, 627 P.2d 864, 865 (1981). Equity regards substance not form. Skaggs Drug Ctr. v. General Elec. Co., 63 N.M. 215, 226, 315 P.2d 967, 974 (1957). The Department’s argument, if successful, would result in Chino’s paying two inconsistent taxes for one taxable event. Because of the indemnity agreement, savings to the taxpayer claiming equitable recoupment (Teco) would necessarily redound to the benefit of the other taxpayer (Chino). But cf. Siemens Energy & Automation, Inc., 119 N.M. at 323, 889 P.2d at 1245. When a party indemnifies another from liability upon which the action is grounded, that party becomes the real party in interest. See United States v. Bureau of Revenue, 69 N.M. 101, 103, 364 P.2d 356, 357 (1961). The relationship of a liability insurer who is obligated to defend the insured and pay the resulting judgment is characterized as one of identity of interest. See State ex rel. J.E. Dunn Constr. Co. v. Sprinkle, 650 S.W.2d 707, 710 (Mo.Ct.App. 1983); see also Arthur W. Andrews, Modern-Day Equitable Recoupment and the “Two Tax Effect:” Avoidance of the Statutes of Limitation in Federal Tax Controversies, 28 Ariz. L.Rev. 595, 604 (1986).
{13} The Department, nonetheless, would have us conclude that the indemnity agreement is irrelevant by relying on Continental Inn v. New Mexico Taxation & Revenue Department, 113 N.M. 588, 591, 829 P.2d 946, 949 (Ct.App.1992), for the proposition that “contracts between a taxpayer and a third party regarding the payment of taxes cannot shift the taxpayer’s legal incidence of the tax as between the state and the taxpayer.” In that case, however, two inconsistent taxes were not imposed on the same party for a single taxable event; instead, the purchaser and the seller disputed who was liable under the contract for payment of the taxes. Id. at 589, 829 P.2d at 947. We are not persuaded by the Department’s reference to Continental Inn.
{14} Because we agree with the hearing officer that the particular circumstances of this case create a strict identity of interest between Teco and Chino, we are also unpersuaded by the Department’s reliance on United States v. Dalm, 494 U.S. 596, 110 S.Ct. 1361, 108 L.Ed.2d 548 (1990). In Dalm, the United States Supreme Court indicated that equitable recoupment can only be brought as a defense in a timely proceeding. Thus, the Department argues that Chino cannot raise equitable recoupment because its action for a refund is time-barred. The Department’s argument would be persuasive if Teco and Chino had no identity of interest for purposes of this action, just as the taxpayers in Siemens Energy & Automation, Inc. were separate. However, because the indemnity agreement gives Teco and Chino a strict identity of interest, then Chino, as the real party in interest in Teeo’s protest, may raise equitable recoupment as a defense to the Department’s claim for taxes owed, and not as an independent claim.
{15} So far, we agree with the reasoning of the hearing officer in favor of the taxpayers and against the Department. However, despite the correct analysis of the three criteria for equitable recoupment, the hearing officer denied taxpayers’ claims, and in doing so the hearing officer looked beyond these elements and performed its own balancing of the equities against the taxpayer. In weighing factors outside those required to satisfy equitable recoupment, the hearing officer gave considerable weight to Teco’s negligent failure to determine its own tax liability and to Chino’s negligent failure to file the required tax on the correct form. The hearing officer was also impressed with the Department’s lack of culpability. While we agree that Teco and Chino appear to have been negligent, we disagree that negligence of this kind is relevant to considerations of equitable recoupment.
{16} The hearing officer justified this additional inquiry into equity by looking to language in Vivigen, Inc. that “[n]o conduct