Almost 20 percent of Americans 65 and older are now working, according to the latest data from the U.S. Bureau of Labor Statistics. That's the most older people with a job since the early 1960s, before the U.S. enacted Medicare.

ecause of the huge baby boom generation that is just now hitting retirement age, the U.S. has the largest number of older workers ever.

When asked to describe their plans for retirement, 27 percent of Americans said they will "keep working as long as possible," a 2015 Federal Reserve study found. Another 12 percent said they don't plan to retire at all.

Why are more people putting off retirement? 

They need the money

Three in five retirees surveyed by the Transamerica Center for Retirement Studies said making money or earning benefits was at least one reason they had retired later than they planned to. Almost half said financial problems were their main reason for working past 65.