Bob Ginsberg, a retired production manager for an educational publisher, is worried that he does not know any of the logins and passwords for online accounts belonging to his partner or brother and they do not know his.

At 72, he said his concern was not about Facebook or e-mail. It was for their financial lives, which have migrated online, making paper account statements anachronistic. Now, when people die without disclosing their financial affairs to anyone, there is often no paper trail for heirs to follow.

“You’d never know someone else’s financial arrangements, but if it was paperwork you’d have a clue,” Ginsberg said. “I’m entirely comfortable doing absolutely everything online. But if I have to take over for my brother or my partner, I don’t have any of their information.”

In its annual Wealth and Worth study, released last month, U.S. Trust said 45 percent of the high-net-worth people it polled had not organized passwords and account information for their digital lives in a place where heirs or an executor would find them. (By contrast, the bank said that 87 percent knew the location of important documents and most had a will.)

Much has been written about how family members struggle to get access to the e-mail and social network accounts of loved ones who have died. But far less attention has been paid to the logins, passwords and answers to security questions that will give access to an online financial life.

In an era when far fewer records are kept on paper, spouses and children may not even know that some accounts exist.

“It’s not only something that needs to be addressed with an individual dying,” Chris Heilmann, chief fiduciary executive at U.S. Trust, said. “If an individual becomes incapacitated, people typically plan for someone to have a durable power of attorney so someone can step in and handle your affairs. But now you’re finding the attorney has to deal with your digital issues. They have to access your computer; they have to pay bills for you.”

Tougher than a safe-deposit box

Sharing the access to a person’s most important financial details is a lot harder than telling loved ones that everything they need to know is in a safe-deposit box. What can people do?

There are many websites and tools that allow people to upload their accounts and passwords in so-called digital vaults. They promise security and a one-stop shop for disparate digital lives. But they often go unused.

People need to record their account information and passwords just as they need to make an appointment to draw up a will. And that seems to be the problem.

Joel Feldman, a retired garment manufacturer, said he had an estate plan but he had been reluctant to write down all of his logins and passwords and give them to his son. He also does not use a financial adviser, who would know some of that information.

“It does concern me,” Feldman said. “I keep saying I’m going to make a CD of my bank statements and put it in my safe deposit box, but I don’t do it.”

Kieran Clifford, a retired vice president for finance from Lucent, said the password to his Gmail account was stolen. By combing through past e-mails, the hacker found a Fidelity statement, got the account number, and e-mailed his broker at a separate firm to transfer $250,000 to a Hong Kong bank. Everything had the same password — his initials and date of birth.

“The e-mail said I’m going out to a meeting and you won’t be able to contact me so go ahead and do the transfer,” Clifford said. Fortunately, his financial adviser called him before doing anything, and they now have an agreement that any move must be confirmed by phone.

Like many things, it sometimes takes a scare to get people to act. After the incident, Clifford, 65, said he wrote down his passwords and gave them to his daughter.

For people who are not highly organized and pragmatic about their estate plans — and that is most people — it seems that short of a crisis they need a persistent adviser to push them. Heilmann said that when his firm reviewed traditional estate plans with clients it got them to draw up digital plans, as well.

Heilmann said people need to think about five things to ensure that everything goes smoothly with their digital financial lives if they become incapacitated or die: they need to maintain a list of their digital information; send the information to someone they trust; make sure other people know who has the information; leave instructions for how everything should be handled, and note all of this in an estate plan and update it regularly.

For those considering these steps, another issue arises: fear that someone else has access to their financial life. Louise Gunderson, a managing director at UBS Wealth Management, said she encouraged clients to upload their information to a secure system that allowed whomever they designated to see the account information but not to move the funds.