Some two-thirds of wealth holders in a new study from Merrill Private Wealth Management reported that they had never talked with family members about how or why they intended to pass on their assets.
Nearly half said they planned to do so at some point, or assumed family members already knew their plans.
But 10% of study participants were adamant about not divulging details of their estate plan, mainly because they considered the information personal and no one else's business.
The study examined whether that was a good decision.
"This research is designed to help families make better decisions and secure the promise of wealth, including the impact it can have within and beyond one's family and lifetime," Andy Sieg, Merrill Lynch Wealth Management's president, said in a statement.
Phoenix Marketing International conducted an online survey in 2018 among 656 high-net-worth and ultra-high net worth adults with at least $3 million in investable assets, not including the value of their primary residence.
The survey found that compared with decisions about saving, investing, spending and other day-to-day finances, those concerning family money ranked as the most important and hardest to make. Among these were gifting to family and charities, dividing assets among heirs and establishing trust provisions or limitations.
Only 33% of survey respondents said they had informed their family of lifetime gifts already made or committed to, such as assets held in a trust, funding of education or a down payment on a first house.
Seventy-two said they had not informed family about their philanthropic commitments.
Asked what was the most important idea to communicate to family members when discussing wealth, respondents' top response was to be a good steward and handle family money wisely.