Under pressure from federal authorities, the Swiss bank UBS is closing the hidden offshore accounts of its well-heeled American clients, potentially allowing their secrets to spill into the open.
In a step that would have once been unthinkable in the rarefied world of Swiss banking, UBS will shut about 19,000 accounts that prosecutors suspect have gone undeclared to the Internal Revenue Service.
UBS will transfer the assets to other banks or other divisions within UBS, or will mail checks directly to the account holders, creating paper trails for federal prosecutors who are examining whether UBS clients used such accounts to evade taxes.
The clients now face stark choices: they can cash their checks, and thereby alert the authorities to any potential wrongdoing, or not cash them, effectively losing their money.
Or they can transfer the money to new banks, a procedure which, in the case of foreign banks, requires depositors of more than $10,000 to report the new account to the Treasury Department.
“You can either take that check and throw it in the woods, or deposit it somewhere and get busted,” said a UBS client, who asked not to be named because of the investigations into UBS and its clients. “There’s nowhere to hide.”
Americans can use offshore accounts, provided they disclose them and pay taxes on their holdings. UBS, the world’s largest private bank, said in July that it would stop offering to American clients offshore private banking services that are not declared to the I.R.S. Prosecutors contend that UBS helped wealthy Americans hide about $18 billion, thereby evading taxes of $300 million each year.
UBS clients who open new accounts at other foreign banks must disclose those accounts’ assets to the Treasury Department.
But because prosecutors claim that some UBS clients failed to make adequate disclosures in the past or lied on their tax returns about holding offshore accounts, the authorities may view the new disclosures as criminal evidence, not just of tax evasion but also of money laundering, a more serious offense.
Some tax lawyers, citing recent conversations with the Justice Department, argue that UBS clients who transfer their assets to new accounts at United States banks could also be seen as engaged in money laundering.
“Any movement of money from UBS somewhere else can be a violation of U.S. money laundering laws,” said Bruce Zagaris, a tax lawyer who represents several UBS clients.
UBS is struggling to maintain its centuries-old tradition of Swiss banking secrecy amid mounting legal pressure from the Justice Department to turn over client records.
It began handing over some records last summer, causing consternation in the Swiss banking community. The checks and transfers will create paper trails because they move through bank clearing systems.
Karina Byrne, a UBS spokeswoman, declined to comment on Thursday on whether UBS would turn over facsimiles of documents recording transfers. “UBS is progressing with the closings in an orderly fashion,” she said.
Some American clients who have approached the I.R.S. about disclosing hidden UBS accounts have discovered that the bank has temporarily delayed closing their accounts by up to three months.
The delay could help the clients because the I.R.S. is more likely to become suspicious if offshore money is moved just as account holders come forward.
William M. Sharp Sr., a tax lawyer who represents several UBS clients, said, “UBS has been very supportive of their American clients who have chosen to undergo disclosure.”
Still, he added that “our view is that if the account is closed and funds are moved to another institution, here or abroad, it could make the case tougher for the clients before the I.R.S., because it could be new violations of money-laundering controls.”
A version of this article appeared in print on January 9, 2009, on page B1 of the New York edition.