Florida man hid $1.1 million from the IRS. How did he do it?

A Florida man on Tuesday pleaded guilty in New York to criminal charges for concealing as much $1.1 million in offshore accounts, even after learning that U.S. authorities were cracking down on wealthy Americans evading taxes.

Bernard Kramer, 83, pleaded guilty to conspiracy and submitting false tax returns, stemming from a scheme that prosecutors said ran for a quarter century and involved an undeclared Swiss bank account he referred to as "Hot Lips."

Kramer also agreed to cooperate with prosecutors in ongoing investigations, according to U.S. District Judge Alvin Hellerstein, who accepted Kramer's plea in Manhattan federal court.

According to court papers made public on Tuesday, Kramer, who has also lived in New Jersey, began evading taxes around 1987 when he opened the undeclared account at an unnamed Swiss bank.

Upon learning in 2008 that U.S. authorities were probing UBS AG for helping U.S. taxpayers conceal accounts,Kramer remained determined to keep hiding his money. In around March 2010 he arranged to move it to a new, undeclared account at an Israeli bank that was also not named, the papers show.

Kramer failed to report interest and income from these accounts to the Internal Revenue Service from 1987 to 2012 and failed to file a U.S. Treasury form known as the Report of Foreign Bank and Financial Accounts, or FBAR, detailing his holdings, the papers show.

During Tuesday's court hearing, Kramer said he met regularly in New York with a representative of the Swiss bank to discuss his account and that "it was understood" the account's existence would remain a secret from tax authorities. He and bank staff used the code name "Hot Lips" to refer to the account, prosecutors said.

His defense lawyer, Brian Ketcham, declined to identify the banks after the hearing.

Dozens of U.S. taxpayers have been charged in the United States since the crackdown on using Swiss bank accounts to evade U.S. taxes became public.

More than 45,000 Americans have paid about $6.5 billion in back taxes, interest and penalties under voluntary IRS amnesty programs, the agency said in June.

In May, Credit Suisse Group AG agreed to pay roughly $2.6 billion in penalties and pleaded guilty to helping Americans avoid taxes, in settlements with various regulators. UBS agreed in 2009 to a $780 million penalty.

Kramer faces up to five years in prison on the top count against him and more than $600,000 in restitution and penalties, prosecutors said.