Shulman reported the voluntary disclosures under a leniency program as the U.S. and Swiss governments announced the criteria used in an agreement for UBS AG to hand over data on 4,450 accounts. The IRS and U.S. prosecutors are scouring the new data to help pursue banks and advisers that foster tax evasion, Shulman said.

"We have now gained access to thousands of taxpayers and bank accounts that we have never had before," Shulman told reporters in a conference call in Washington. "It has sent a shock wave around the world. It has showed we are serious about piercing the veil of bank secrecy."

Americans with undeclared offshore accounts have been under growing pressure since Switzerland agreed Aug. 19 to hand over data to the U.S. on as many as 4,450 UBS accounts to settle a lawsuit in which the U.S. had sought as many as 52,000 accounts.

The partial amnesty program, announced in March, let taxpayers repatriate offshore assets and avoid jail by paying back taxes, interest and reduced penalties. The tax agency will take 20 percent of a disclosed account's assets based on its peak value in the previous six years. In cases of inactive accounts, the agency will confiscate as little as 5 percent.

Almost double

The more than 14,700 voluntary disclosures announced yesterday are almost double the amount the IRS reported on Oct. 14, one day before the partial amnesty program ended. They are in addition to the accounts UBS must turn over to the IRS.

Switzerland said yesterday it will turn over details of UBS accounts held by U.S. residents who had more than 1 million Swiss francs (US$985,000) in undeclared assets.

Other benchmarks include U.S. citizens who were beneficiaries of "offshore company accounts," according to a statement distributed by the Swiss Justice Ministry in Bern yesterday. In both cases, the review period is between 2001 and 2008, and there has to be a suspicion of "tax fraud and the like."

Swiss authorities withheld details of how the accounts were selected for 90 days so the information wouldn't interfere with the IRS's voluntary disclosure program. The criteria will be used as a template by the U.S. to pursue banks and tax evaders in other financial centers, lawyers say.

UK, France, Italy

The IRS may hope the publication of the Swiss criteria will persuade more people to disclose their accounts as the U.S. is joined in its search for undeclared money by authorities in the U.K., France and Italy, said Stephanie Jarrett, a law partner at Baker & McKenzie in Geneva.

"There are still a lot of people out there who want to sort things out," Jarrett said before the criteria were released. "It's going to get harder and harder for people who are undeclared."

It is legal to have offshore bank accounts as long as taxpayers disclose their existence to the IRS and pay taxes on the income. Americans often open accounts in other countries for non-tax-avoidance reasons including having access to funds while living or traveling abroad or hiding money from creditors or former spouses.

Billions of dollars

"We are talking about billions of dollars coming in to the U.S. Treasury," he said. "The real impact is for the next 10 and 20 years people not going and hiding assets."

U.S. Senator Carl Levin of Michigan, the Democratic chairman of a panel that exposed UBS's strategies for recruiting wealthy American tax-cheats in two hearings, said the criteria for turning over UBS names to the IRS were "disappointing" because they stopped short of pursuing all 52,000 Americans initially suspected of cheating on their taxes.

"The tortured wording and the many limitations" in the criteria show the Swiss government is "trying to preserve as much bank secrecy as it can for the future, while pushing to conceal the names of tens of thousands of suspected U.S. tax cheats," Levin said.

The Obama administration is working with House Ways and Means Committee Chairman Charles Rangel of New York and Senate Finance Committee Chairman Max Baucus of Montana to promote legislation to tax the U.S. income of banks that refuse to reveal the identities of Americans with undeclared accounts. A Credit Suisse group AG official earlier this month warned that approach would hurt foreign investment in the U.S.

Voluntary disclosure

About 12,000 of the voluntary disclosures came after the U.S. and Switzerland reached the August settlement on UBS, Shulman said. IRS officials who briefed reporters after he spoke said a large number of disclosures made in the closing days of the program came from what they called the Far East. The officials spoke to reporters on the condition they not be identified by name.

Shulman said the IRS will use the voluntary disclosures to expand a global effort to find tax evaders. The IRS has identified accounts in 70 countries on every continent except Antarctica.

"What they are really looking for is people who knew what they were doing," said attorney Thomas Zehnle of Bryan Cave LLP in Washington. Those people are "taking real efforts to conceal their ownership and who are trying to actually use the money, as opposed to somebody who has inherited an account from a Holocaust survivor."

Hiring staffers

The IRS plans to hire 800 people in the next year and increase staff in eight overseas offices, including Hong Kong, Shulman said last month. The agency also will open offices in Beijing, Sydney and Panama City.

"This is a mega-trend, and the IRS is going global," William Sharp, a lawyer at Sharp Kemm PA in Tampa, Florida, said before the criteria were released. "The days of bank secrecy are over."

People who came forward voluntarily can avoid criminal prosecution and their identities will remain a secret under a federal law requiring tax records to be kept confidential.

Ordinarily, the IRS can seize the higher of US$100,000 or 50 percent of an offshore account's value when the holder deliberately didn't disclose it to the Treasury Department. The penalty can apply each year that required forms weren't filed, so after three years of noncompliance an account holder can owe 150 percent of the account's value.