Another challenge for retirees or people close to retirement is the near absence of guidance on complicated financial questions like how long their money needs to last—something actuaries study long and hard to learn how to do. This was not a big issue when defined benefit pension plans supported more people, but they no longer do.  Read MorePensions struggle to live up to their promises  "People shouldn't be expected to estimate how long they will live," said Hiltonsmith. He said most people are withdrawing their money too quickly, leaving little or nothing for their final years, partly because they underestimate how long they are likely to live and partly because they do not have enough savings.  In the past, financial professionals used to talk about a 4 percent drawdown as a good rule of thumb for retirement. But that approach is no longer so apt, said David John, senior strategic policy advisor at the AARP Public Policy Institute. It's not safe anymore to assume that your investments will earn what that 4 percent rule was based on. Given current rates of return, the 4 percent rule "gives you a 15 to 30 percent chance that you will run out of money," he said.  But determining how much to draw down isn't easy. Unlike savings calculators, which many financial firms offer online to help investors determine what they need to put away, tools for calculating retirement spending are rare. "When it comes down to retirement income, you can find annuity calculators, but you really can't find anything that's more complex," said John.  Read MoreFor millions of Americans, the 401(k) experiment is a failure
Employers and 401(k) plan administrators offer plenty of advice when employees are saving. When it's time to use the money, guidance is scarce.