In the five years since Bill Gates and Warren Buffett created the Giving Pledge, 193 individuals have made the simple promise to give more than half of their fortune away in life or in death. This week, another 16 people joined the initiative, including Chobani yogurt founder Hamdi Ulukaya and Scottish oil baron Ian Wood.
Signing the pledge has brought glowing press coverage, video testimonials from Bill Gates and invitations to annual conferences in luxurious resorts with fellow billionaires such as Ray Dalio and Pierre Omidyar.
Less publicised is the fact that the crux of the pledge is subjective. Signatories are under no legal obligation to donate any of their money, and sometimes fail to give away anywhere close to half. Charity regulations and estate law can block public disclosures, and Buffett and Gates don't ask pledge takers to prove a thing.
"It's really thinking about how iconic figures providing inspiration and support can inspire and serve as a model for society," said Robert Rosen, the Giving Pledge coordinator as Director of Philanthropic Partnerships for the Bill & Melinda Gates Foundation. "We aren't looking to add any additional complexity," said Rosen.
Public disclosures of lifetime and estate giving of the 10 deceased billionaires who signed the pledge show that fulfillment of the pledge varies widely. Only two have given away more than $1 billion, and they donated the money before the initiative was started.
The Giving Pledge emphasizes that it's a moral pledge. This distinction has a very real legal purpose: it eliminates the ability of Giving Pledge signers to sue fellow billionaires who fail to give, according to David Scott Sloan, an attorney and national head of the estate law practice at Holland & Knight.
"When I give money to charity and I pledge to pay it over five years, I actually sign a contract," Sloan said. "These are all people who sign lots of pledges like that and wanted, I'm sure, to make it very clear it's a moral direction as opposed to a legal direction."
Rosen says the Gates and Buffett effort is a long-term project to reset levels of giving.
"The conversation continues to evolve with what's expected and what becomes the norm of generosity, both in terms of the impact and the impact it has - that's our true north star," Rosen said. "People do it in different ways and at different times because it's such a personal decision."
Gates and Buffett are leading by example. The two richest Americans with a combined fortune of $156 billion, according to the Bloomberg Billionaires Index, have put more than $46 billion into the Gates foundation. Michael Bloomberg and three other co- founders of Bloomberg LP, the owner of Bloomberg News, have all signed the pledge.
Gates said in a 2010 interview with Fortune that he considered giving away half one's fortune the "low bar." But defining what constitutes half is difficult, a point exemplified by the estate of Albert Ueltschi.
A Kentucky-born pilot of Swiss ancestry, Ueltschi became a billionaire by selling his FlightSafety International pilot-training schools to Warren Buffett's Berkshire Hathaway for stock that was valued at almost $2 billion when he died. He also developed a close friendship with Bill Gates.
When the pair asked him to join the Giving Pledge, Ueltschi didn't hesitate. He pledged the majority of his fortune to fight blindness.
"I have never seen a hearse pulling a U-Haul trailer. You can't take it with you," Ueltschi wrote in his Giving Pledge letter dated September 18, 2012.
He died one month later at age 95.
In his will, Ueltschi commanded nothing go to charity if there was no US estate tax, as had been the case two years prior. Because an estate tax was in effect, it triggered a clause that one-third of his estate go to charity.
All told, in life and death the billionaire gave $260 million away. Another $200 million will come once the Internal Revenue Service issues final acceptance of the estate's tax return, his son James said in a phone interview. Once that happens, his father will have met the Giving Pledge, the younger Ueltschi said.
"We did the calculations and that is what it was, so that is what it is," James Ueltschi said.
While the elder Ueltschi may have built a fortune of as much as $4 billion, according to data compiled by Bloomberg, much of the money wasn't legally his at death, his son said.
"My father had various vehicles to provide for his various beneficiaries through tax planning that he did throughout his life," Ueltschi said from the New York headquarters of HelpMeSee, a cataract-focused charity the family formed in 2010 to solve preventable blindness worldwide. "Those assets don't belong to my father and they do not belong to his estate. The Giving Pledge is half whatever is left."
According to tax returns, Al Ueltschi and his foundation have given $5.1 million to HelpMeSee.
How a fortune can be many billions of dollars and satisfy the Giving Pledge with what seems to be far less is a function of how death bequests are structured, said attorney Sloan. Typically, a percentage of after-tax assets is donated, rather than a fixed dollar amount.
"If you have $1 billion, you need to be sure that by the time you are done paying taxes, debts, heirs, etc., there's $500 million to give," he said.
In reality, a pledge to give half of a $1 billion fortune ends up being half of $600 million, assuming the standard 40 per cent US estate tax is levied. It can take years for the IRS to sort out in large estates in situations where a percentage is bequeathed.
The IRS declined to comment on estate tax procedures, agency spokesman Matthew Leas said in an e-mail.
Tax calculations are delaying the bequest of billionaire George Mitchell. The oil tycoon signed the pledge in 2010 and died two years ago. His foundation has yet to receive any funds from the estate pending IRS settlement of the tax return, said Katherine Lorenz, president of the Cynthia & George Mitchell Foundation and the couple's granddaughter. She declined to elaborate on the specific reason for the delay.
"My grandparents were very public that they were very dedicated to giving the majority of their wealth to charity issues, but I don't feel at liberty to say how much until the estate settles," Lorenz said.
The couple gave away $400 million during their lives, according to Lorenz. At the time of his death, Mitchell had a net worth of at least $3 billion, according to data compiled by Bloomberg.
Determining how Harold Simmons's pledge was met is even harder to ascertain. Simmons built an $8 billion fortune staging leveraged buyouts of Arby's franchise operators and sugar beet processors in the 1980s. The Texan and his wife Annette joined the Giving Pledge in 2011. The couple gave at least $350 million to charity through 2013, based on foundation tax returns and other public disclosures.
"Though we have made many philanthropic gifts during our lifetimes and plan to do more, we have also established trusts to carry on this giving after my death," they wrote in their Giving Pledge letter.
In the will he signed three weeks before his death in December 2013, Simmons gave two of his four daughters, Lisa Simmons and Serena Simmons Connelly, assets worth $6 billion through inheriting Contran, a holding company that controls stakes in four public companies worth $4.5 billion and cash from the sale of another company in 2013. Annette Simmons received about $700 million in preferred stock and other assets.
The billionaire indicated in his will that two charitable foundations could receive $400 million. Those foundations weren't funded because their creation was contingent on his heirs not being alive, estate lawyers disclosed during a legal challenge by Bloomberg News on the will's redaction last year.
The heirs - Lisa, 60, and Serena, 45 - run the Harold Simmons Foundation, which disclosed net assets of $56 million in 2013 after accounting for $38 million in refundable loans owed to the late billionaire, according to its tax return. The sisters and Annette Simmons didn't return e-mails and phone calls seeking comment.
Gates Foundation's Rosen said scrutinising specific estates is secondary to the bigger picture.
"Looking at the complexity of each estate might miss the bigger point around what we're trying to do and making sure that this is in many ways an incredibly powerful and yet incredibly simple proposition," Rosen said.
Associating with the world's greatest investor and its richest person could mean billionaires are drawn in by the public accolades, with the act of charity a lesser consideration, said Pablo Eisenberg, Senior Fellow of the Center for Public & Nonprofit Leadership at Georgetown University.
Leonard Tow and his wife Claire became billionaires through Citizen Utilities and Century Communications in the 1990s. In 2012, he signed the Giving Pledge with Claire, who died last year. He declined to disclose how much they gave or plan to give away. Their Tow Foundation has net assets of $196 million and has doled out $85 million since 2001, according to tax returns.
"It's like joining a club, that's all it is," said Tow in an April phone call. "There wasn't any thinking about it."