LG Group Chairman Koo Kwang-mo is belatedly found to have filed a complaint against the South Korean tax administrative agency, claiming that the inheritance taxes imposed on him were excessively hefty, according to the business circles on Sunday.

Koo took legal action against the head of the National Tax Service’s regional office in Yongsan-gu, central Seoul, in the latter half of last year to request the cancellation of inheritance tax overpayment. The chairman jointly filed a suit with his stepmother and two stepsisters, the source said.

They are reportedly seeking the court's judgment on the valuation of their 1.12 percent stake in LG CNS, which they inherited from the late former chairman Koo Bon-moo who died in May 2018. In the process of paying inheritance tax, there was reportedly a disagreement between the current chairman and the tax authorities over the stake value in the unlisted IT service firm.

If they win the case, the amount of money that Koo’s family could receive is about 1 billion won ($766,600) -- a fairly small amount relative to the 99 billion won inheritance tax levied on the LG Group family.

The heirs, including the current chairman, have been paying the succession tax for five years under the country’s yearly installment payment scheme since they reported the amount of inheritance tax in November 2018.

Koo will fully pay the 720 billion won worth of inheritance tax owed by the end of this year.

The late chairman owned an 11.28 percent stake in LG Corp. Koo Kwang-mo inherited an 8.76 percent stake, becoming the largest shareholder of the conglomerate with subsidiaries including LG Electronics, LG Display and LG Chem.