Here is a list of items that can help determine whether you may be a whistleblower with a false claims case:
You have unique, first-hand information about how a potential fraud is being perpetrated against the government. Tax frauds can be included, as can frauds against states and municipalities (if those governments have their own false claims laws).
Your information is based on what you saw or heard. If information about a fraud is publicly known, and you are not an insider, it will be very difficult to pursue a case.
You did not plan or initiate the fraud, but you may have been instructed to participate by your employer. You tried to complain—usually to no avail, and you may have been retaliated against as a result.
You are committed to the prosecution of the fraud, which may take several years for the government just to investigate. You are also willing to be publicly known as a whistleblower at the appropriate time.
The fraud involves significant amounts of money. The potential defendant should be a large or publicly-held company with substantial assets that could pay a recovery.
The company’s fraud was intentional. An honest mistake, technical violations, or interpreting an ambiguous rule or regulation in one’s favor is not fraud.
You have some corroboration for your knowledge of the fraud, which is likely a combination of documents, what you have learned, and what others have told you. Of course, you should not obtain any evidence through illegal means.