Under the qui tam provision of the False Claims Act, the relator (plaintiff) files an action on behalf of the U.S. Government. The Act allows a wide variety of people and entities to file a qui tam action. The more common types of relators are as follows:

Employees: An employee who blows the whistle on his or her employer is one of the most common types of relators. Experience has shown that employees normally file qui tam actions against their employers as a last resort after repeated attempts to resolve the issues internally (very often through so-called internal "hotlines") have met with negative results. An important provision of the 1986 amendment protects employees who file an action, or assists in furthering an action, against job retaliation by the employer.

Former employees: This is another common type of whistleblower who files a qui tam action. A former employee files a qui tam action based on his or her direct knowledge of fraud on the part of their former employer. In many cases, the former employee was terminated or quit under duress as a result of trying to blow the whistle internally.

Competitors and Subcontractors: Another type of relator is the competitor of the company being charged or an employee of the competitor who has direct knowledge of the fraud being committed. Also, companies or persons who subcontract with a government contractor have filed qui tam actions against the contractor.

State and Local Governments: The 1986 Amendments gave state and local governments the power to be relators in qui tam actions. Since then, there have been a number of qui tam actions filed by local and state governments against contractors and medical providers as a means of recovering state or local revenue lost as a result of the schemes.

Federal Employees: A much maligned group are former and current federal employees who file qui tam actions. The Act, as amended in 1986, does not exclude federal employees from being a relator. However, when a federal employee does file a qui tam action, it results in considerable controversy and numerous court challenges as to whether the employee, due to his or her responsibilities, are obligated to disclose the fraud. The courts have been mixed on whether a federal employee has standing under The Act and the Justice Department remains hostile toward this type of relator.  Concerns have been raised as to whether a federal employee filing an action presents a type of conflict of interest.

Other types of qui tam relators have included public interest groups, corporations and other private organizations. However, organizations as relators have raised questions as to whether they can meet the "public disclosure" provision of the law. Some courts have dismissed organizations as relators for not being able to meet that provision.

The Act also allows a relator to file a qui tam action even if a "public disclosure" was made prior to the action being filed as long as the relator meets the "original source" test - the relator had "direct and independent knowledge" of the information on which the allegations were based and the relator "voluntarily provided the information to the government" prior to filing the action.