Williams did, however, leave money in a trust for his three children, according to TMZ, unlike Philip Seymour Hoffman or James Gandolfini.
Williams' publicist stated several days after the actor's death that that trust is no longer part of Willams' estate plan.
But experts say the kind of trust Williams had in effect at one point could have been structured much more effectively.
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The trust assets were reported to be structured so they would be distributed to Williams' children in three increments: at age 21, 25, and 30. But those may not be the optimal times for the kids to receive large sums of money, experts say.
Trust provisions like these are "fairly common, but far from ideal—especially because I would have to assume that his estate would be quite large," said David Mendels, director of planning at Creative Financial Concepts, a financial planning firm in New York. "Thus one third could easily be millions of dollars, which is quite a lot of responsibility to drop on a 21 year old."
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Many wealthy people worry that leaving too much money to children at a relatively young age will destroy their motivation, or worse.
There are other concerns with fixed distribution times, Mendels said. What if a child is getting divorced at 30, and suddenly comes into substantial assets that then have to be divided? Or what if a child is at risk for a lawsuit, and losing would mean handing over the assets?
Rubin said the more modern way of structuring a trust for children is to give them responsibility for appointing the trustee at a certain age. That way they can, if they choose, appoint someone who will let them draw down assets—or they can choose to leave the assets in the trust, where they are not vulnerable to a lawsuit or a divorce settlement.
"He definitely thought about his estate planning and did something smart, but not as smart as it could have been," Rubin said.