Only half of these wealthy individuals say they have a will

Young adult, millennial stepping out of Lamborghini, wealth
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Millionaires are expected to pass down as much as $30 trillion to their children over the next few decades. But a new study suggests that neither wealthy kids nor their parents are ready for that cascade of inheritances.

RBC Wealth Management questioned 3,105 people in the U.S., U.K. and Canada with an average net worth of $4.5 million, and $500,000 in minimum investible assets. Only about half of the survey's respondents said they had a will, and only 1 in 4 reported having a full strategy for transferring their wealth to the next generation.

The firm also found that wealthy parents are waiting far too long to educate their kids about their wealth-transfer plans, waiting until they reach age 27, on average. The most common reasons for delay were the parents' lack of preparedness, or a fear that the inheritors weren't yet old enough.

"Despite the volume of money in motion, inheritors are being left in the dark," the report said. "Most have little to no advance preparation. Without prior instruction or guidance during the process, individuals find themselves making monetary decisions in a vacuum."

Even those who have already received their inheritances may not have been fully prepared, according to the RBC. Only 35 percent of respondents who already received an inheritance were made aware of it ahead of time, the study found.

This was true even for the truly rich. Among those worth more than $10 million, less than half were prepared for their inheritance in advance, RBC said.

Correction: The headline of this story has been corrected to accurately reflect the wealth of the survey's respondents.