BOSTON — The CVS pharmacy chain agreed to pay the state $450,000 because it did not offer a senior citizen’s discount to Medicaid program recipients and therefore overcharged the medical aid program, state officials said Thursday.

CVS offers a 20 percent discount plan to customers over the age of 65. However, when seniors received medication on the Medicaid program, the pharmacy did not offer the discount when billing the state, said Jack Rogers, a spokesman for the state Department of Public Welfare.

Similar billing discrepancies also were found at Brooks pharmacies, and the state expected to reach a settlement with that company in the near future, Rogers said.

Neither CVS or Brooks could be reached for comment after business hours on Thursday.

The state expects to save up to $200,000 a year with the added discount, Rogers said.

The billing discrepancies came to agency’s attention after an employee from a Brooks pharmacy approached reporters at Boston’s WNEV-TV, now WHDH, Rogers said.

The pharmacies were apparently allowing senior citizens to sign up for the discount program, but Medicaid patients weren’t applying because their bills were paid by the state, Rogers said.

Last week CVS agreed to pay the $450,000, which represents two years of overpayments, after an audit of their records, Rogers said. The company also agreed to reprogram their computers to meet the new policy, he said.