W. Va. Code § 23-2-13

The interest due on payments pursuant to §23-2-9(d)(1) and §23-2C-8(d)(1) of this code shall be the prime rate plus four percent rounded to the nearest whole percent. The prime rate shall be the rate published in the Wall Street Journal on the last business day of the prior fiscal year reflecting the base rate on corporate loans posted by at least 75 percent of the nation’s 30 largest banks: Provided, That in no event shall the rate of interest charged to a political subdivision of the state or a volunteer fire department exceed 10 percent per annum.