A posting error on the county land roll is expected to reduce ad valorem taxes next year by about $60,000, Tax Assessor Mike Lewis told supervisors on Monday.

Lewis said the apparent computer error occurred when appraisal maintenance figures were posted to the land roll earlier this month.

The discrepancy was detected upon review of the land roll's assessed values, he said.

The error reduced the true value of the county between $300,000 and $500,000, which could result in about $60,000 less in ad valorum taxes than previously anticipated.

"I don't have an explanation for it," Lewis said of the error.

He is currently working with Delta Computer Systems to address the issue.

Lewis told supervisors that there was no "time stamp" to show where any of the records were manually changed.

"It was not a human error but nobody is able to give me an answer," Lewis said.