The actress is being sued by bosses at City National Bank (CNB) for $85,000 (£53,125), who allege Doherty agreed to make one principal payment plus interest on 1 June (09).
In court documents obtained by TMZ.com, the papers claim the star "made, executed and delivered to CNB a promissory note (a contract to provide payment) in the original sum of $90,000.00."
On June 18 (09) the agreement was amended to allow her up until 1 September (09) to pay the cash, but she allegedly failed to meet the deadline.
Executives at City National Bank have now filed suit accusing the actress of breach of contract and unjust enrichment. They are demanding the outstanding payment plus interest, and ask Doherty to pay for the lawsuit costs and attorney fees.