“I offer my sincere apologies for the error itself and for the failure of the initial letter to communicate effectively, including about the nature and scope of the problem, and Harvard’s proposed response,” Hausammann wrote. The letter went on to clarify the details of the situation and what the University would do to assist those who were affected.

While Halperin said in an interview with The Crimson on Sunday that the steps Harvard aims to take to compensate employees are “reasonable,” he raised concerns about the four-year time span in which no official caught the mistake after the life insurance policy was changed.

“I don’t know what happened,” Halperin said. “Somebody in both Human Resources and in payroll should have been aware about what was going on, but apparently they didn’t connect.”

According to the Harvard University Fact Book, the University employed more than 16,000 people in the 2011-2012 academic year, the last for which there are publicly available records. During the 2013 fiscal year, the University paid more than $1.5 billion in compensation.

Director of the Harvard Union of Clerical and Technical Workers Bill Jaeger said that, as a Harvard employee who was directly affected by the mistake and as the leader of the University’s largest union, the mistake is a troubling oversight.

“Our union doesn’t spend a lot of time or resources double checking because we want to be able to assume that, in terms of tax reporting and compliance in general with the federal legal framework, the benefits programs are being competently managed,” Jaeger said. “So it’s a little unsettling to have this big question just pop up and cast doubt on the quality of the management of our programs.

—Staff writer Christine Y. Cahill can be reached at christine.cahill@thecrimson.com. Follow her on Twitter @cycahill16.

—Staff writer Amna H. Hashmi can be reached at amnahashmi@college.harvard.edu. Follow her on Twitter @amna_hashmi.