Deceased rapper Mac Miller was 26 and had a will — similar to that of Michael Jackson

Mac Miller, a 26-year-old American rapper and music producer who died Sept. 7 in California, had a will, and its contents are similar to those of musical phenom Michael Jackson.

The fact that Mr. Miller even had a will may surprise some financial advisers, given Mr. Miller’s youth. Other famous, much older musicians — Aretha Franklin and Prince, to name recent examples — died without wills, tying up their substantial fortunes in a complex legal process.

Mr. Miller, whose legal name was Malcolm McCormick, reportedly had a net worth of about $9 million at the time of his death, the cause of which officials have yet to verify.

The Pittsburgh native released his first album, “Blue Slide Park,” in 2011; it was the first independent album to debut at No. 1 on the Billboard 200 chart since 1995. Since then, he’s released several other albums, including “Watching Movies with the Sound Off” (2013), “GO:OD AM” (2015) and “The Divine Feminine” (2016). His 2018 album, “Swimming,” was released last month.

“What impresses me about this guy is, he’s single, young, has no kids, and yet took the time to do this,” said Charlie Douglas, an estate planner. “Really rare for anybody, no less someone who’s an artist in the music industry.”

(More: Aretha Franklin didn’t have a will — and she’s not the only celebrity)

Mr. Miller left his entire estate to a trust, the Malcolm McCormick Revocable Trust, according to his will. He named himself as trustee of the trust.

Michael Jackson took the same measure in his will, giving his estate to the Michael Jackson Family Trust, of which he was trustee. Mr. Jackson died in 2009.

The use of revocable trusts in estate planning is a common strategy for celebrities and residents of California, and has become more popular with the general public, estate planners said. Mr. Miller lived in the San Fernando Valley, and Mr. Jackson also resided in California.

A revocable trust is essentially a “will in a different form,” said Bruce Steiner, estate planning attorney with Kleinberg Kaplan Wolff & Cohen.

Unlike wills, revocable trusts take proceedings out of probate court, which is a notoriously challenging arena for Californians. Estate executors in California must deal with the court during the administration process more than in “most every other state,” Mr. Steiner said.

But perhaps more importantly, revocable trusts are private ordeals, whereas terms of a will are a matter of public record. Some news reports have said Mr. Miller left his estate to his parents, but experts said this is purely speculation — it’s impossible to know from the details of his will.

“We have no idea who gets what,” Mr. Steiner said. “Maybe he left it to his favorite charity, or maybe to someone other than the parents and siblings and didn’t want us to know.”

The key to ensuring an estate stays out of probate is funding a trust during one’s lifetime, Mr. Douglas said. In Mr. Miller’s case, that would have meant retitling assets like a house and investment accounts so they weren’t owned in his name as Malcolm McCormick the individual, but rather as trustee of the Malcolm McCormick Revocable Trust.

“Your trust is like buying a new car, but it won’t run correctly if you don’t put gas in the car,” Mr. Douglas said. “The gas for the revocable trust is you retitling the asset during your life so that you avoid probate.”

Mr. Douglas, who heads a family office, said Mr. Miller’s will serves as a “pour-over” will — it’s a catch-all in the event Mr. Miller forgot to retitle an asset, which would then “pour over” into his trust and remain out of probate.

“That’s really the only purpose this will serves,” Mr. Douglas said.

“This is similar to Michael Jackson’s thing,” he said. “We don’t know exactly what happened [to estate assets] because everything pours over.”