Home Depot cofounder Bernie Marcus has a plan for how to spend his fortune, he told The Atlanta Journal-Constitution. After the 90-year-old billionaire dies, 80 to 90% of his total wealth will go to his foundation to build centers to help veterans with disabilities around the country, fund medical research, and provide care for children with autism.

Aside from philanthropy, Marcus is also a major political donor: He supported, and intends to again support, Donald Trump’s presidential bid.

The Atlanta-based billionaire has a net worth of $5.9 billion, down from its peak of $10 billion in September 2018, according to the Bloomberg Billionaires Index.

Marcus and his wife, Billi, signed The Giving Pledge in 2010. He has already donated $2 billion to more than 300 charities, according to The Washington Post.

According to The Atlanta Journal-Constitution, Marcus refused to name the exact sum he would donate, but the newspaper estimated that Marcus could give away a total of $6 billion to charity in his lifetime based on his commitment to donate 90% of his wealth when he signed The Giving Pledge.

Donation cause No. 1: Trump's campaign

Marcus was one of Trump's largest donors in 2016, giving $7 million to Trump's campaign through outside groups, according to the Center for Responsive Politics. Marcus said he planned to financially support the president in the 2020 election, according to The Atlanta Journal-Constitution.

Read more: Less than 1% of the world's billionaires donate to housing and shelter charities. Here are the top 10 causes the world's richest people give their money to

Donation cause No. 2: philanthropy

Marcus is a noted philanthropist in Georgia, having donated $250 million to fund the construction of the Georgia Aquarium, which opened in 2005. Marcus has also made contributions to an autism center and Grady Memorial Hospital in Atlanta, according to The Atlanta Journal-Constitution.

Healthcare and medical research were the fourth most common cause that billionaires donated to in 2018, Business Insider previously reported. Marcus' political donations are less common among billionaires: only 12.4% donated to public-affairs causes. Education charities are the most popular, receiving donations from 79.5% of billionaires.

"I've got all the houses I need," Marcus told The Atlanta Journal-Constitution. "I live very well. My kids are taken care of. Everything I live for now is finding the right things to put my money into and that can give me a rate of return in emotion and doing good things for this world."

Marcus cofounded Home Depot in 1978 with Arthur Blank after they were fired from their jobs at another hardware store, according to Forbes. Marcus was the company's first CEO and retired in 2002. Bloomberg reported that the chain of home-improvement superstores now has more than 2,200 locations in North America and made $108.2 billion in revenue during the 2018 fiscal year.