Enlarge By Chip Somodevilla, Getty Images IRS Commissioner Douglas Shulman, seen here at the American Institute of Certified Public Accountants' 35th Annual National Tax Conference in October, said Tuesday that the crackdown on offshore account holders has generated significant tax revenue. Federal tax investigators plan to pursue criminal charges against some of the roughly 4,000 American clients of UBS whose secret account data have been turned over to U.S. authorities under a 2009 treaty agreement that targeted the Swiss banking giant. "You can expect to see criminal prosecutions coming out of them," IRS Commissioner Douglas Shulman said in a Tuesday phone interview with USA TODAY as he announced UBS had handed over information for the account owners suspected of evading taxes. "We're going to obviously partner very closely with the Justice Department and determine how many and which ones." Along with potential prosecution, Shulman said each of the previously secret account holders will face "a full-blown audit" plus full tax repayments and penalties unless they were among approximately 15,000 Americans who received leniency by coming clean during an IRS voluntary disclosure program last year. An additional 3,000 American account holders have filed voluntary disclosures since the program ended, as the IRS and the Department of Justice kept up the pressure by announcing more than a dozen criminal cases against owners who secretly stashed assets offshore. Specifics of how the IRS will handle those UBS clients are under discussion now, Shulman said. Promising "more to come," he said the information turned over by UBS and gathered via the voluntary disclosure program has put IRS investigators on the trail of secret, American-owned accounts "involving numerous banks, advisers and promoters from around the world." "It's certainly not limited to one country," Shulman said. "There are certainly other banks that we're in the process of pursuing right now that appear to have similar patterns." He declined to provide specifics or discuss last month's tax fraud convictions of father-and-son hotel developers Mauricio Cohen Assor and Leon Cohen-Levy. They were accused of directing the $33 million transfer of proceeds from the sale of a New York hotel to an HSBC account in Switzerland held under the name of a Panamanian firm. The money was never reported to the IRS. Shulman sketched the next steps of the ongoing crackdown on offshore tax evasion as he announced that the IRS has formally withdrawn a legal summons filed against UBS. Federal prosecutors dismissed a parallel tax evasion case against the Swiss bank last month. UBS agreed to pay a $780 million fine in that case after admitting its bankers had made trips to the U.S. to help clients evade taxes. The IRS ultimately expects to obtain information for more than 7,500 accounts owned by Americans. Some of the additional account holders have filed appeals with Swiss courts. Information will be forwarded as the courts rule on those cases, the Swiss embassy said Tuesday. Shulman said the IRS crackdown has generated new tax revenue. "But collecting additional revenue for past misdeeds is not the only important consideration," he said. "It is important that we are bringing thousands of U.S. taxpayers back into the system so they properly report and pay their taxes for years to come." Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more