Ramsey County is promising refunds this week to nearly 700 residents and businesses who were double billed this month for property taxes.

A problem with the county's electronic payment system, resulting in duplicate withdrawals totaling $3.75 million, was identified Monday, according to a news alert posted to the county's website.

The error affected 678 taxpayers who made online payments between Sept. 29 and Oct. 2, county officials said. Those property owners were charged a second payment in the same amount last Friday.

In an email Wednesday, county spokesperson Rose Lindsay said residents and businesses had started to receive refunds Tuesday. She said all duplicate charges should be refunded within two business days.

"The county is taking this issue seriously and we are working to understand the immediate needs of residents as well as the broader unique impacts to each resident and business," Lindsay wrote.

Officials determined the mistake was an "isolated incident" affecting those who submitted payments via the Automated Clearing House system, Lindsay said. Those who paid by check, credit card or debit card were not billed twice.

In the year and a half since Ramsey County started working with its electronic payment vendor, CORE, Lindsay said no other issues have been reported.

County officials said they have a list of all affected taxpayers, who should have received an email update Tuesday. County staffers were working Wednesday to ensure that everyone had been reached.

Lindsay said officials also are encouraging anyone "experiencing immediate impacts from the double withdrawal" to call 651-266-8500 for assistance.