COLUMBIA, S.C. (AP) — Nearly 400 nonprofits and public employers will receive bills totaling more than $542,000 after South Carolina's unemployment agency mistakenly undercharged employers for three quarters.

The Department of Employment and Workforce is notifying employers this week of a computer programming error that resulted in $8.6 million worth of paid-out benefits not being properly recorded. However, businesses won't be charged that amount.

The bills are going to so-called "reimburseable" employers — nonprofits, local governments and school districts that choose to be billed after laying people off in a pay-as-you-go system. The recalculations won't affect most businesses that pay unemployment insurance taxes into a trust fund based on their layoff history. But it will boost some into a higher tax rate for 2013, agency spokeswoman Adrienne Fairwell said Wednesday.