Despite warnings to the contrary, many Americans aren't saving for retirement. About half of households age 55 and older have no retirement savings, according to a May report by the Government Accountability office.
But for employees being blasted with open enrollment information this October, it's never too soon to start. When it comes to retirement, it's all about the time value of money, Matt Sommer of Janus Capital Group told CNBC's "Power Lunch" Tuesday.
Depending on your age, you may want to pick different options when starting a retirement fund, Sommer said. In your 20s, for instance, you have the power of compounding on your side, and you can put away just a third of someone who starts in their 30s or later, Sommer said.
For instance, a 25-year-old medium earner aiming to retire at 62 would have to save 15 percent of their yearly income at a rate of 4 percent return. Starting at age 35, the rate jumps to 24 percent, according to a 2014 study by the Center for Retirement Research at Boston College.