By Se Young Lee SEOUL (Reuters) – The heirs of ailing Samsung Group patriarch Lee Kun-hee face one of the biggest inheritance tax bills ever, and appear to have little option but to pay up. By some calculations, Lees 45-year-old son Jay Y. Lee, the groups presumed heir apparent, and his two sisters could be on the hook for about $6 billion in tax under South Koreas top level inheritance tax rate of 50 percent. The elder Lees assets, held mostly in shares of Samsung Electronics , the worlds dominant smartphone maker, and Samsung Life Insurance , have a market value of around 13 trillion won ($12.7 billion). The typical strategy is to adjust the amount of assets before death, take advantage of deductibles that are legally permitted or gift assets to push down the inheritance tax bill in advance.