About a third (34 percent) of all workers have increased their planned retirement age in the last 12 months, and for older workers, 44 percent of those aged 50 and over plan to delay their retirement, compared with only 25 percent of those under 40, according to Watson Wyatt.

Based on a survey of 2,200 full-time workers in February, Watson Wyatt finds that although the average planned retirement age for all employees is 65 years old, half (50 percent) of those aged 50 or more plan to retire at age 66 or later. According to the survey, 76 percent of older workers (aged 50 to 64) cited the decline in the value of their 401(k) accounts as the most important reason why they are planning to postpone their retirement, followed by the high cost of health care (63 percent) and higher prices for basic necessities (62 percent). Of this group, more than half (54 percent) also indicated that they will work for at least three years longer than previously expected, Watson Wyatt reports.

The survey also found that workers who participate in a defined contribution-only plan are more likely to delay retirement than those with a defined benefit plan. Only approximately a quarter (26 percent) of those with defined contribution plans, including 401(k)s, plan to retire before the age of 65, compared with 41 percent of those with defined benefit plans, Watson Wyatt says.