Hundreds of CUNY retirees are being shortchanged out of their full pensions because of data glitches that started three years ago.

The workers were due retroactive raises back to 2012 after a 2016 contract settlement. Those increases impacted the amount of their pensions, which are based on the average of the last three years of pay.

But CUNY hasn’t been able to provide accurate data to the New York City Teachers Retirement System, according to Bill Friedheim, the head of the retirees chapter of the Professional Staff Congress, the union representing CUNY faculty and staff.

“They put in all this time dedicated to students,” Friedheim said.

“They had productive work lives at the city university, contributed immensely and now they’ve got to wait years to get their proper pensions.”

As many as 300 people may be affected.

Aggrieved pensioners have pleaded with the CUNY Board of Trustees to fix the problem, first at a December meeting and again last month.

“I think it’s absurd,” said William Gargan, who retired in 2018 after 39 years at Brooklyn College as a professor and librarian.

He said it took the TRS 10 months to calculate his pension and he opened the letter with the final figure only to see “they based it on the wrong salary.”

“CUNY’s to blame,” he said. “TRS is to blame for this, too.”

Kathleen Kovach, who retired from Brooklyn College in 2014, said she estimated she was missing out on $60 a month.

“It shouldn’t take three years to adjust my pension,” she said.

A CUNY spokesman blamed outdated information systems at both the university and TRS “which could not handle the volume of data that resulted from the seven years of retroactive increases.”

“The university is working closely with TRS to provide all the data required,” Frank Sobrino said.

But a TRS spokesman said that “CUNY has not been able to provide all of the necessary data in the format required and communicated to them.”