NEW YORK — Twenty-six big U.S. companies paid their CEOs more last year than they paid the federal government in tax, according to a study.

The study, by the Institute for Policy Studies, said the companies, including AT&T, Boeing and Citigroup, paid their CEOs an average of $20.4 million last year while paying little or no federal tax on ample profits, according to regulatory filings. On average, the 26 companies generated net income of more than $1 billion in the U.S., the study said.

The study blasted tax rules allowing unlimited deductions for CEO “performance-based” pay, like many stock options. It said the five biggest performance payers among the 26 companies took $232 million of these deductions last year.

Among the “kingpins” it criticized was CEO James McNerney Jr. of Boeing. It said he got $18.4 million in pay last year while his company received a tax refund of $605 million.

The study also laid into Citigroup for paying CEO Vikram Pandit $14.9 million while the bank received a net $144 million in tax benefits.

Eighteen of the 26 companies received cash back or credits to apply against tax in the future, according to the report.

The study, a 45-page attack on the corporate tax code, said deductions and credits are allowing companies to lavish big pay packages on executives so they can cut their tax bills while Washington gets less money in a time of trillion-plus deficits.

“Our nation’s tax code has become a powerful enabler of bloated CEO pay,” the study said.

To calculate tax, the study used companies’ own math based on accounting rules.