Buffett, 94, plans to donate 99.5 per cent of his remaining wealth, valued on Friday at $US149.7 billion ($A229.5 billion) according to Forbes magazine, to a charitable trust overseen by his daughter and two sons when he dies.
In a letter to Berkshire shareholders on Monday, Buffett said three potential successor trustees have been designated if his daughter Susie, 71, and sons Howard, 69, and Peter, 66, cannot serve.
He said each is somewhat younger than his children, well known to them and "makes sense" to all of them.
"I've never wished to create a dynasty or pursue any plan that extended beyond the children," Buffett wrote.
"But these successors are on the wait list. I hope Susie, Howie and Peter themselves disburse all of my assets."
Buffett also said he is donating another $US1.14 billion of Berkshire stock to four family foundations.
That boosts his giving to more than $US58 billion since 2006, when Buffett pledged most of his fortune to the foundations and to the Bill & Melinda Gates Foundation, which has received more than $US43 billion.
He has donated 56.6 per cent of his Berkshire shares.
Buffett has led Omaha, Nebraska-based Berkshire since 1965.
He still owns 14.4 per cent of its stock and plans to continue donating shares to the five foundations during his lifetime.
After his death, his children will have about 10 years to give away his remaining wealth, and must decide unanimously which philanthropic purposes it should serve.
Susie Buffett leads the Susan Thompson Buffett Foundation, which funds reproductive health and is named for Buffett's first wife, and the Sherwood Foundation, which supports Nebraska non-profits and early childhood education.
Howard Buffett heads the Howard G Buffett Foundation, which works to address global hunger, combat human trafficking and mitigate conflicts.
Peter Buffett leads the NoVo Foundation, which has initiatives focused on marginalised girls and women as well as indigenous communities.
Berkshire is a $US1 trillion conglomerate, owning businesses such as the BNSF railway and Geico car insurance, and stocks such as Apple and American Express.
In his letter, Buffett acknowledged his advancing age but signalled no intention to step aside.
"Father time always wins," he said.
"To date, I've been very lucky but - before long - he will get around to me."
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