SEOUL -- Ahead of Monday's anniversary of the death of Samsung Group Chairman Lee Kun-hee, the family behind South Korea's biggest conglomerate began the process of paying a world-record inheritance tax of 12 trillion won ($10.3 billion).

Lee's family held a small memorial service on Monday morning. In attendance was son Lee Jae-yong, vice chairman of Samsung Electronics and de facto leader of the group, who was released on parole in August after serving more than half of a 30-month prison term for corruption.

To his father, "Samsung was his life," said the younger Lee, also known as Jay Y. Lee. "By taking on bold challenges, he built the Samsung we know today."

Hong Ra-hee, the late chairman's widow, has signed an agreement to sell a 0.33% stake in Samsung Electronics to a bank, according to a disclosure by South Korea's Financial Supervisory Service. The shares have a market value of about $1 billion.

Hong inherited 2.3% of Samsung Electronics, making her the company's largest individual shareholder.

Lee Boo-jin, Lee's eldest daughter, will reportedly sell a 1.95% stake in Samsung SDS, the group's software development arm. Second daughter Lee Seo-hyun will reportedly sell 1.73% of Samsung Life Insurance, among other shares.

Lee Jae-yong is expected to pay off his inheritance tax in part by using cash, dividends and proceeds from real estate sales. He will not sell shares in core companies, meaning the younger Lee and his family would maintain their control over the conglomerate.

Lee Kun-hee, who is credited for transforming Samsung from a budget TV maker into a global powerhouse, left behind assets totaling 26 trillion won, including real estate and fine art. South Korea imposes an inheritance tax of at least 50%, one of the highest in the world.

Lee's family will pay the 12 trillion won tax in installments over five years. Many of the 23,000 art pieces, which include antiques designated as South Korean national treasures and Impressionist paintings, have been donated to museums. These works are slated to be on display as the Lee Kun-hee Collection.