A version of this article first appeared in CNBC’s Inside Wealth newsletter with Robert Frank, a weekly guide to the high-net-worth investor and consumer. Sign up to receive future editions, straight to your inbox.

A new estimate for the great wealth transfer has sparked a debate over how many trillions of dollars will pass from baby boomers to their heirs, and how it will be spent and invested.

Last week, Visa Business and Economic Insights released a new projection for the great wealth transfer, estimating that $36 trillion in baby boomer wealth will be passed down to Gen X and millennials over the next 20 years. The figure is a fraction of the widely cited estimate from Cerulli Associates, which says $105 trillion will pass from older generations to heirs by 2048.

The more than $60 trillion gap between the two studies has raised new questions about the size and impact of the great wealth transfer. Some say it will be the largest in history, dramatically reshaping wealth management, charity and the global wealth landscape. Others say its impact will be far more limited and simply marks a continuation of long-term inheritance trends.

The dueling Visa and Cerulli numbers highlight just how important the estimates have become for wealth managers and other companies overhauling their businesses to prepare for the next generation of wealth.

Visa, as a credit card payments company, focuses its study on the amount of inherited wealth that will be spent by everyday American consumers. Cerulli, being a financial research firm, focuses its study on the total wealth being transferred, including the outsized share of fortunes being passed down by the ultra wealthy. While Cerulli focuses on all wealth transfers in coming decades, Visa looked only at transfers from baby boomers.

“We wanted to go through and inspect how much money will actually be spent,” said Wayne Best, chief economist at Visa. “A lot of people think about the $93 trillion or $124 trillion and think ‘All that money’s going to be available for spending; this is going to be incredible.’ That’s why we went through the kind of the step-by-step process.”

Visa’s process started with the total amount of wealth held by today’s baby boomers, which it put at about $93 trillion. The report then stripped out liabilities, which includes mortgage debt, of $5 trillion and subtracted the wealth of the top 1%, estimated at $28 trillion.

Best said the top 1%, or those with wealth of at least $12 million, approach money very differently from the rest of consumers. They spend a much smaller share of their wealth and they tend to buy different things.

“They don’t spend like the rest of us,” Best said. “They’re buying yachts and airplanes. It’s all great for the economy, but that’s not what the average person really thinks of. So we removed that top 1%, to put this more on a normal or level playing field.”

Visa then stripped out the retirement spending of baby boomers, which could be larger than expected. Because boomers are living longer and spending their wealth more than past generations, Visa estimates their retirement spending at $16 trillion. It also subtracted $8 trillion for charity and taxes.

In addition, Visa focused its analysis exclusively on the wealth being transferred from baby boomers over the next 20 years. Cerulli looked at transfers from all generations by 2048, which includes members of the older Silent Generation, as well as the younger Generation Xers, who are now between 46 and 61 years old.

After taking out the debt, the fortunes of the top 1%, retirement spending, taxes and charity, Visa estimates that boomers will pass on only $36 trillion of their $93 trillion in wealth.

Of that $36 trillion, they estimate that $28 trillion will go to savings and investments and $8 trillion will go to spending. The $8 trillion will be spent mainly on cars, homes, travel and retail.

“You know, $8 trillion in spending is nothing to sneeze at,” Best said.” It’s a significant amount of money. And it’s additive. But we wanted to put that in perspective because when you start throwing around trillions of dollars it can get confusing very quickly.”

Cerulli, by contrast, sought to estimate the total wealth being passed down by all wealth groups, of all ages, by 2048.

Chayce Horton, Cerulli’s associate director of wealth management, said the biggest impact of the great wealth transfer will be in wealth management, rather than consumer companies.

Half of the more than $100 trillion being passed down will be from high net worth or ultra-wealthy families, he said. The first transfers in the coming years will be to spouses, mainly women. Cerulli estimates that $4 trillion will go to spouses before being passed down to children and other family members.

“When you look at that demographic, on average, spouses are a couple years younger, and those spouses live a couple years longer,” Horton said.

Cerulli said it does factor in retirement spending, taxes and debt. It also estimates that about $18 trillion of $124 trillion in total transferrable wealth will go to charity — leaving a total of $106 trillion going to heirs and spouses.

Gen Xers will be the first recipients, followed by millennials and then Gen Z. Gen X will inherit $14 trillion in the next 10 years, but millennials will eventually inherit the most, estimated at $46 trillion in the next 25 years.

Horton said it would be a mistake for the wealth management industry or any company serving wealthy clients to discount the impact of the great wealth transfer and the acceleration of inherited wealth. He said that one of every four wealth management clients currently come from inherited wealth — second only to business owners and founders, and ahead of corporate executives.

“The focus of our report when we do this analysis is understanding where the wealth is today, and where that wealth will be moving tomorrow so the wealth and asset management industry can adapt,” Horton said. “Something that we continue to emphasize as an important consideration for the wealth management industry, is making sure that they have those relationships across spousal lines, as well as intergenerational lines.”