New York City accidentally deposited nearly $300 million Thursday in the bank accounts of about 31,000 retired police officers and firefighters, officials said.
The errant contributions were made overnight, and the city promised to take back the money by Friday.
The city's Financial Information Services Agency blamed the situation on "a coding error."
City Comptroller Scott Stringer's office said in a statement that officials are informing the retirees of the error and advising them "not to spend the money."
Pensioners who retired after 1968 receive an annual payment, which has been $12,000 since 2008.
The agency said the error occurred as city technicians prepared to automate child support payments following bank-transfer protocols previously used for the retirees' payouts.
In one instance, the technicians accidentally initiated actual money transfers instead of just testing the system, resulting in the extra payments.
"The coding error has also been corrected, along with implementation of additional safeguards to ensure that a control failure of this nature does not occur again," the agency said in a statement.
Reversing the deposits may cost the city money, but Stringer spokesman Eric Sumberg could not say how much.