This might not come as a surprise, but many who are saving for/living in retirement, as well as financial advisers, have a lot of misconceptions about retirement-income planning.

So says Jamie Hopkins, author of just published Rewirement: Rewiring How You Think About Retirement.

People, he says, got the saving for retirement part done. Not so much what some call the decumulation phase or spend-down phase.

“We know that we need to put money away,” Hopkins told me in an interview. “We know we need to start early. We know we need to take some risk, but a lot of that stuff gets kind of flipped on its head once we get to retirement…”

Yes, once we get into retirement, well, “people aren’t very good at that,” he says.

In fact, research has shown that “people are much worse at the income literacy than they are general financial planning literacy, and that’s what kind of spurred on this book,” says Hopkins, who is also the co-director of the New York Life Center for Retirement Income and a professor at the American College of Financial Services.