The Marion County auditor’s office has voided the sale of liens on 54 properties auctioned at the county’s most recent annual and surplus tax sales.

The reason: A county contractor failed to follow the law and notify property owners by first-class mail about the sale of their properties. The law requires owners to be notified by both certified and first-class mail.

The 40 buyers of the 54 properties — mostly vacant homes and empty lots — will get their bid money refunded, plus 6 percent annual interest. The interest totals $4,900, said Claudia Fuentes, deputy auditor.

She said it’s unclear whether Guts Inc., the Thorntown company that was paid to do the notifications, will reimburse the county for the interest payment.

The 54 properties will be relisted in a future tax sale, Fuentes said. Hundreds of other properties in the sales, held last October and this January, weren’t affected by the legal glitch.

Katherine Crist, who bought one of the 54 properties — a house near Fountain Square — said the county’s mistake means she won’t be able to move into the home this month as she planned.

“I’m mad,” said Crist, a single mother of two who lives in a trailer. “It was a perfect opportunity for us” to own a house.

Crist said she submitted a high bid for the house of $2,400, which was the amount of delinquent taxes owed.

The county holds the tax sale for properties owing back taxes or unpaid fees. Owners have anywhere from 120 days to a year after the sale to pay off the back taxes or fees and hold onto their property. If they don’t, the seller takes possession.