Tax lawyers Jonathon Moore and Charles Bruce already had their hands full defending themselves from allegations that they botched a client’s matter, resulting in millions of dollars in Internal Revenue Service back taxes and penalties. Now the lawyers’ insurance company has come forward saying it no longer wants to cover the malpractice case.

The two lawyers, name partners in Washington, D.C.-based Moore & Bruce, are being sued, along with their firm, in the U.S. District Court for the District of Columbia. The complaint, filed in May 2008 by cell phone entrepreneur James De May, claims the firm made mistakes while setting up a tax shelter, such as sending certain forms to the IRS late, that cost De May $7.5 million. All the while, the firm was racking up excessive fees, the complaint alleges. De May is seeking $10 million in damages.