Her success was sometimes clouded by problems with tax inspectors and alleged plagiarists. Heyer chose not to file lawsuits against the suspected literary thieves, but tried multiple ways of minimizing her tax liability. Forced to put aside the works she called her "magnum opus" (a trilogy covering the House of Lancaster) to write more commercially successful works, Heyer eventually created a limited liability company to administer the rights to her novels. She was accused several times of providing an overly large salary for herself, and in 1966 she sold the company and the rights to seventeen of her novels to Booker-McConnell. Heyer continued writing until her death in July 1974. At that time, 48 of her novels were still in print; her last book, "My Lord John", was published posthumously.