Data from the health and retirement study linked with Social Security records — in which participants were asked about their retirement plans at 58, when they’re thinking about a potential retirement date but not likely to have already retired— was analyzed to identify a target income replacement rate, which would provide each household enough income to maintain its preretirement standard of living.

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The researchers then projected an actual replacement rate for each household at each age, based on its own circumstances, and compared the target and projected replacement rates to identify a target retirement age.

Researchers then compared planned retirement ages with target retirement ages, when individuals would have enough income to maintain their preretirement standard of living, to identify gaps, and found that households with lower SES were more likely to have a gap than higher-SES households.

Researchers found that, even after controlling for demographic/financial characteristics as well as shocks, the retirement gaps for households in the third and the highest SES quartiles are 0.9 and 1.3 years less than those in the lowest SES quartile.

“These results have important policy implications,” the study concluded, “because they suggest that the big problem is premature retirement among low-SES households. This same group has seen little improvement in health and life expectancy and faces poor job prospects. It may well be that their retirement shortfalls cannot be bridged by working longer and that other solutions will be needed.”