Under the previous procedures, the informant would receive nothing. The new rule would allow the informant to claim a share of the $50 million, Keith said.
"A lot of those things fall into those buckets," Zerbe said of whistleblower tips. Among others, Zerbe represents Bradley Birkenfeld, a former Swiss banker at UBS AG who blew the whistle on clients including Igor Olenicoff, a California billionaire convicted of cheating on his taxes. Despite providing information to U.S. authorities, Birkenfeld was imprisoned for helping Olenicoff and others.
Blum said the regulations likely won't affect claims such as those by his clients. Those claims involved people who hid income from the IRS in undeclared overseas accounts.
"That's probably not going to affect the kind of stuff I've been involved in because these people simply didn't report income," he said.
The 2006 law spurred a legal industry built around submitting claims.
After the law was enacted, the Miami-based Ferraro Law Firm, which had specialized in personal-injury cases involving cancers related to asbestos, opened a Washington office that recruits and represents clients making whistleblower claims. The firm has said it made several claims alleging more than $1 billion in unpaid taxes.