New procedures were put in place to prevent the error from happening again, the department said.

Taxpayers in the US state of Louisiana got an unexpected windfall when a computer error issued their tax refunds a second time, local media reported on Saturday.

The state's Department of Revenue cautioned recipients of the wrongly-paid windfall: "Do not spend it." If they have, they must pay the money back in 30 days.

"An error in an electronic payment system caused 66,780 state individual income tax refunds issued on Tuesday, March 12 to be issued a second time on Wednesday, March 13," the department said on its website.

The duplicate refunds totaled more than $26 million, it said, adding that the state is working with financial institutions to recover the overpayments directly from recipients' bank accounts.

New procedures were put in place to prevent the error from happening again, the department said.