In new court documents obtained by People Magazine, Baumgartner, 49, asked Costner to provide any and all financial records relating to an extramarital affair.
In the documents filed Monday in the Santa Barbara County Superior Court, Baumgartner requested Costner, 68, provide “expenses paid by you, or any person at your request or on your behalf, relating to any extramarital romantic relationships.”
Through his legal team, Costner disputed the request and denied ever having an affair.
Costner’s lawyers argued he “has no responsive documents for ‘extramarital romantic relationships’ in which he engaged because he engaged in none.”
The legal team went on to claim that Baumgartner’s request was “propounded only for purposes of harassment” and is “over-broad as to time period and subject matter, burdensome, oppressive and impermissibly compound.”
Costner added that he “does not know for a fact” whether or not Baumgartner had an affair of her own.
Neither Costner nor Baumgartner have made public statements about the issue.
Also this week, Baumgartner accused Costner of being “evasive” about his finances. According to Entertainment Tonight, Baumgartner argued the Yellowstone star’s financial reporting in the divorce proceedings has been “deficient.”
She asked for Costner to submit details about his “anticipated income” and claimed he has “failed to produce a myriad of bank account and credit card statements which are directly relevant.”
Costner called the request for his financial documents “burdensome, oppressive and harassing.” He said he is unable to provide certain statements because they relate to his upcoming film Horizon and are “highly confidential.”
Costner and Baumgartner were married for 18 years. Baumgartner filed for divorce on May 1, citing “irreconcilable differences.” The couple have three children together: Cayden, 15, Hayes, 14, and Grace, 12.
The affair allegations and request for financial documentation are the most recent dramas to emerge from the couple’s divorce proceedings.
In July, Costner accused Baumgartner of charging US$100,000 (C$132,060) in legal expenses to his credit card throughout May and June.
“Christine began charging large sums on the credit cards payable to her divorce attorneys and forensic accountants. She gave me no advance warning each time she did so,” Costner argued at the time.
In June, Costner claimed Baumgartner was violating the terms of their prenuptial agreement when she allegedly refused to vacate his southern California house. The actor said the agreement, which was signed when the couple married in 2004, gives Baumgartner 30 days to exit the property after filing for divorce.
After much debate, Baumgartner exited the property in July. She refused to move out of the multimillion-dollar estate until she and Costner reached a child support agreement. She requested Costner pay $248,000 (about C$327,900) a month in child support.
Though Costner initially said he could pay $51,900 (about $70,750), a judge ordered him to pay $129,755 (almost $176,900) per month until the matter can be settled in court.
Baumgartner also requested her soon-to-be ex-husband pay $350,000 (nearly C$462,900) in lawyer’s fees and $150,000 (about C$198,300) in forensic accounting costs.
Costner allegedly already paid Baumgartner $1.4 million (C$1.8 million) owed to her as a condition of their prenuptial agreement, which she has since said she felt pressured to sign.
Costner, who no longer stars in the hit TV series Yellowstone, is currently in post-production for his latest film Horizon: An American Saga, which he starred in, produced and directed.
Costner and Baumgartner are expected to appear in court in August and September.