QUESTION
               You asked for our opinion on whether Linda S.'s (hereinafter Claimant's) second marriage
                  to Robert S. (hereinafter second husband) was valid for purposes of determining Claimant's
                  eligibility for divorced wife's benefits based on her first husband's (number holder)
                  work record.
               
               ANSWER
               For the reasons set forth below, we believe that Claimant is not entitled to benefits
                  based on the number holder's account due to the existence of her marriage to her second
                  husband.
               
               SUMMARY OF EVIDENCE
               On May 18, 2004, Claimant filed an application for divorced wife's benefits on the
                  work record of her first husband. Claimant and her first husband were married in April
                  1960 and divorced in March 1976.
               
               In 1976, Claimant began living with her soon-to-be second husband in California. Claimant's
                  second husband had been married to another woman since May 1973, but had separated
                  from her in March 1976. On November 9, 1978, the Superior Court of California in San
                  Bernadino County entered an Interlocutory Judgment of Dissolution of Marriage between
                  Claimant's second husband and his first wife.
               
               On February 17, 1979, Claimant married her second husband in Arizona. Claimant and
                  her second husband never lived in Arizona, but continued to live together in California
                  until April 1980, when they moved to Texas. The materials you provided us contain
                  a letter dated April 5, 1983, from the second husband's divorce attorney addressed
                  to Claimant in Texas. The letter indicates that Claimant had contacted the attorney
                  regarding her second husband's prior marriage and divorce. The attorney stated in
                  the letter that no final judgment of divorce had been entered. The attorney also recommended
                  that Claimant obtain a nunc pro tunc order to validate her marriage to her second husband (such an order would grant a
                  final judgment of divorce retroactive to November 9, 1978, the date of the Interlocutory
                  Judgment). Apparently, no action was taken to obtain a nunc pro tunc order. Sometime in 1993, Claimant and her second husband moved from Texas to Missouri,
                  and have lived there ever since, apparently as a married couple.
               
               In her May 18, 2004, application for divorced wife's benefits, Claimant stated that
                  she was "NOT MARRIED NOW" and had "only recently learned" that her second husband
                  had not obtained a final judgment of divorce from his first wife. A June 17, 2004,
                  Report of Contact indicates that Claimant told the Agency that while she was going
                  through documents in connection with an application for retirement benefits based
                  on her own work record, she found the divorce attorney's 1983 letter.
               
               ANALYSIS
               A woman is entitled to Social Security benefits as the divorced wife of an individual
                  who is entitled to old-age or disability insurance benefits if she meets several requirements,
                  including the requirement that she not be married when she applies for benefits. See 42 U.S.C. § 402(b)(1) (2004); 20 C.F.R. § 404.331 (2004). Because Claimant's first
                  husband was domiciled in Mississippi at the time she applied for benefits, the Agency
                  applies Mississippi law to determine Claimant's marital status. See 20 C.F.R. § 404.345. Mississippi courts would apply Arizona law to determine the validity
                  of Claimant's second marriage because she and her second husband were married in Arizona.
                  See
                     Miller v. Lucks, 36 So.2d 140, 141 (Miss. 1948); 52 Am. Jur. 2d Marriage § 63 (validity of marriage
                  is governed by law where parties were married) (2004); see also POMS GN 00305.005. Because Claimant's second husband obtained his Interlocutory Judgment of divorce
                  in California, Mississippi courts would apply California law to determine the validity
                  of the divorce decree. See Johnson v. Pogue, 716 So.2d 1123, 1133 (Miss. App. 1998); see also Depper v. Depper, 451 P.2d 325, 327-28 (Az. 1969) (valid foreign decree entered in divorce action
                  entitled to full faith and credit).
               
               Claimant has not demonstrated that she is not married for purposes of entitlement
                  to divorced wife's benefits. Claimant and her second husband were married in 1979.
                  There is no evidence in the file to suggest that their marriage ended, for instance
                  by divorce or annulment. Although Claimant states on her application for benefits
                  that she is "not married now" to her second husband because he never obtained a final
                  judgment of divorce from his first wife, Claimant has not provided any direct evidence
                  or authority for this contention. It is her burden to prove she is not married. See 20 C.F.R. §§ 404.723, 404.728 (claimant is responsible for providing evidence of marriage
                  and divorce). Presumably, Claimant is contending that her second marriage is bigamous.
                  See ARIZ. CONST. art. 20, 2 (prohibiting polygamous marriages); ARIZ. REV. STAT. §§ 13-271,
                  13-273 (1977) (now codified at §§ 13-3606, 13-3607 (West 2004), renumbered by Laws
                  1977, Ch. 142, § 99, eff. Oct. 1, 1978 (criminalizing polygamy)); CAL. CIV. CODE §§
                  4401, 4425 (1977) (now codified at CAL. FAM. CODE §§ 2201, 2210 (West 2004)). However,
                  Claimant apparently entered into her second marriage based on a good faith belief
                  that her second husband's divorce was final, and has been married to him for the past
                  twenty-five years. Thus, the fact that her second husband's divorce was not finalized
                  does not change her status as his putative wife. See 20 C.F.R. § 404.346 (an individual can obtain the status as a putative spouse if that
                  person entered into the marriage with a good faith belief that the marriage was valid
                  despite a legal impediment, i.e., a previous marriage had not ended at the time of
                  the ceremony); POMS GN 00305.055. Here, Claimant can readily clarify her marital status. For instance, Claimant could
                  seek to divorce or annul her marriage to her second husband. If she elected this option,
                  Claimant would satisfy the "is-not-married" requirement for divorced wife's benefits.
                  Until Claimant takes such action, however, there is no basis for the Agency to conclude
                  that she is not married to her second husband.
               
               We also note that even if Claimant had shown that her marriage to her second husband
                  were somehow legally or technically void, she nevertheless likely would be estopped
                  from attacking the validity of the marriage because her conduct since the second marriage
                  indicated a good faith belief in, and reliance on, its validity.
               
               Estoppel is an equitable doctrine. In many instances, in order to effect equity and
                  justice, the law disregards the difference between a valid and invalid/void marriage
                  or divorce. For instance, in California (where Claimant and her second husband lived
                  immediately following their marriage), an individual who has remarried in reliance
                  upon an interlocutory decree may not attack the finality of the decree. See Spellens v. Spellens, 317 P.2d 613 (Cal. 1957) ("The theory is that the marriage is not made valid by
                  reason of the estoppel but that the estopped person may not take a position that the
                  divorce or latter marriage was invalid"); Dietrich
                     v. Dietrich, 261 P.2d 269 (Cal. 1953) (finding second husband estopped from asserting the invalidity
                  of his wife's divorce from her former husband where second husband, in reliance on
                  the divorce, went through a marriage ceremony and lived with wife as her husband for
                  many years); Rediker v. Rediker, 221 P.2d 1 (Cal. 1950); In re Marriage of Recknor, 187 Cal.App.3d 539 (1983). Sitting in equity, the California courts have emphasized
                  the conduct of the party to be estopped (i.e., the party's reliance on a divorce decree),
                  rather than the particular legal defect of the decree. In equity, it is the understanding
                  and actions of the concerned parties which are of paramount importance, not legal
                  form.
               
               It follows that, on the facts you have provided, Claimant would be estopped from attacking
                  her second husband's divorce. The length of time Claimant and her second husband have
                  lived together (apparently twenty-five years) as husband and wife, and Claimant's
                  own statement that she had "only recently learned" that her second husband had not
                  obtained a final judgment of divorce from his first wife, strongly suggests that she
                  had believed herself to be the legal wife of her second husband. Moreover, nothing
                  in the file demonstrates that either Claimant or her second husband sought legal recourse
                  to dissolve their now disputed marriage. Since Claimant actually, and apparently in
                  good faith, relied upon the decree in marrying her second husband, she would be estopped
                  from challenging the decree irrespective of the nature of any legal flaw. In equity,
                  "an interlocutory decree of divorce at least gives color as a judicial determination
                  of divorce." See Spellens, 317 P.2d at 620. Public policy requires the recognition of Claimant's marriage to
                  her second husband, rather than Claimant's "dubious attempt to resurrect" her second
                  husband's original marriage to his first wife. See Spellens, 317 P.2d at 618.
               
               CONCLUSION
               Because Claimant is considered married to her second husband, and is estopped from
                  denying the validity of his prior divorce and, thus, her subsequent marriage to him,
                  Claimant is not entitled to divorced wife's benefits based on her first husband's
                  work record.