Auto insurer Mercury General Corp. said Thursday it will take a $15 million charge in the first quarter after California tax officials ruled that the company did not properly account for certain expenses during a four-year period from 1993 to 1996.

In a filing with the Securities and Exchange Commission, Mercury General stated that the Franchise Tax Board rejected the company’s expensing of management services provided to its insurance company subsidiaries “on grounds that such expenses were allocable to the company’s tax-deductible dividends from such subsidiaries.”

The company said it believes its accounting for the expenses was appropriate and that it will challenge the ruling by the State Board of Equalization, which upheld the tax assessments by the Franchise Tax Board.

Shares of Mercury General rose 0.4 percent to settle at $54.99. The filing came after the close of trading on Thursday.