BOSTON — An accountant has been charged with helping a former state senator file false income tax returns and conspiring to defraud the IRS.

John H. Nardozzi, of Waltham, was charged in an indictment that was unsealed on Monday. Nardozzi was the accountant for former state Sen. Brian Joyce, who was charged last month with accepting up to $1 million in bribes and kickbacks and laundering money through his law office.

Nardozzi is accused of, among other things, conspiring to fraudulently deduct millions of dollars of personal expenses for Joyce as legitimate business expenses of the senator’s law firm.

Nardozzi didn’t immediately respond to a phone message on Monday. It was not immediately clear if he has an attorney.

Joyce’s attorney has said his client is innocent.