The Yonkers Republican was once one of New York's most powerful politicians.
He admitted Friday in a White Plains courtroom that he had obstructed tax laws.
He confessed that he failed to report consultant fees and a real estate commission. He also said a corporation he controlled claimed improper deductions.
Spano's plea agreement with prosecutors indicated he is expecting to be sentenced to 12 to 18 months in prison.
Sentencing was set for June 11.
Spano spent 28 years in the state Legislature, rising to assistant majority leader of the Senate.
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