The actress, who has famously voiced the character of Bart Simpson for more than 20 years, was devastated when her construction boss partner Stephen Brackett died in May 2009.
She is now facing legal action from executives at the American Safety Casualty Insurance Company (ASCIC) over a policy which was taken out to cover Brackett's refurbishment work on a restaurant, which he failed to complete before his death.
The suit from ASCIC alleges Cartwright agreed to act as a guarantor for the policy but is now refusing to cover the expenses which occurred on the project when Brackett's company folded following his suicide.
The paperwork also alleges Brackett ""diverted contract funds"" to the Church of Scientology, of which he and Cartwright were both members.
The lawsuit seeks the $260,000 (£173,333) which was allegedly handed over to Brackett to complete the project as well as various other costs, according to TMZ.com.