The Finance Department says 427 people were overpaid in their pensions and the government is contacting them to recoup the money.
The department says the error was the result of indexing pensions and integrating provincial pensions with the Canada Pension Plan as required when people turn 65.
Finance Minister Ross Wiseman says efforts will be made to minimize the financial impact on pensioners while making arrangements for repayment.
Wiseman says the money is owed to the pension plans affected and its members, not the government.
He says more audit reports and checklists have been developed to avoid the possibility of similar mistakes being made in the future.