Workers’ expectations about working longer before retirement have changed substantially during the past 20 years, based on surveys by my firm.

In general, many workers have not accumulated enough for a financially secure retirement, and so they feel they simply must work longer to maintain the lifestyle they want throughout their retirement.

This change has a key implication for retirement preparation strategies that advisors should recommend.

First, let’s look at what is happening in more detail and then provide an idea for how financial advisors should adjust the advice they provide to clients.

In 1991, only 2% of workers expected to retire between the ages of 66 and 69, and only 9% expected to retire after age 70 or never retire at all, according to joint research by my firm, the Employee Benefit Research Institute. By comparison, 19% of the surveyed workers that year planned to retire before age 60.

Since 1991, savings rates have gone down (until recently) and debt levels have gone up. But workers were not blind to the inadequacy of their accumulations for retirement. They just did not want to reduce their lifestyles as much as they needed to in order to fund retirement. So, many started to plan to work longer.

In the year 2000 survey, for instance, 23% of workers said they planned to retire after age 65 or never. In 2005, that percentage rose to 30%. In early 2010, 42% said they will retire after age 65 or never.

Some might think that the main cause of this trend is Social Security raising the age of entitlement for full benefits from the original age of 65 to (for those born in 1960 or later) age 67. But that is clearly not the case–because the big increase is in the proportion of those planning to work until 70 or beyond.

The characteristics of the people who are planning to retire at age 70 and after are interesting. Their income and financial asset levels are approximately the same as those who plan on retiring at a younger age, and their health is about the same.

But those who are planning to work to, or beyond, age 70 are less likely to have a defined benefit plan and/or money in an employer-sponsored retirement plan.

Also, people planning on working longer are a lot less confident that they will have enough money to live comfortably in retirement, be able to pay for their basic medical expenses, or even be able to pay for their basic expenses.

Clearly, most are planning to work a lot longer because they feel they have to in order to be financially secure in old age.

Those who are planning to work after age 65 have reached such a large proportion (42% of all workers) that adjustment to the primary approach to retirement planning seems necessary. The primary approach says that workers should calculate a number representing how much they must accumulate by a certain date in order to have a financially comfortable retirement.

The approach has merit because it focuses attention on retirement. As a result, many fine calculators have been designed to help people calculate this particular number.

But today’s retirement realities are such that, for many people, that one number is simply not enough. The problem is that many people do not get to work as long as they want. Illness, disability and other uncontrollable factors stop many people from continuing to work. In fact, in surveys I have worked on, about two in five retirees have consistently stated that they had to retire before they planned, usually due to illness or disability.

Of course, the risk of illness or disability goes up with age. With more people planning to work longer, the nation now has workers who, without really being aware of it, are placing themselves at considerable risk of having to stop work before they reached their accumulation goal.

It is relatively easy for people to believe that, if their current rate of savings is not enough, they can simply plan to work until 70. But the risk of waiting to save enough is substantial due to the increasing risk of illness or disability at the older ages.

See the box for a recommendation on a new step in financial planning that would help address the issue.

Just deciding to work longer is a long awaited evidence of realism. But it is a high risk strategy. Financial advisors should stress to clients the need to have the basic accumulation accomplished before the high risk years associated with involuntary retirement.