Almost all American retirees claim Social Security at the wrong time, a new report estimates, which means they will miss out on a collective $3.4 trillion in benefits before they die. While they can tap their benefits as early as age 62, retirees could boost the size of their checks for every year they wait until age 70, when the maximum benefit accrues. The advantage in waiting is substantial: A person eligible for a $725 monthly check at 62 could get a $1,280 check if they wait to start at age 70. United Income, a money management firm that provides financial advice to retirees, teamed up with former Social Security officials to simulate retiree decisions on when to claim benefits, along with factors that include income, wealth, taxes, health status and longevity. Their analysis found that 96% of retirees choose the wrong year to tap Social Security. When to take Social Security is a key decision for America’s elderly, for whom the program has become a critical safety net. About half of older Americans get most of their income from the program. Unlike investments and other sources of retirement income, Social Security benefits are guaranteed to keep up with inflation and last for life. That’s important when half of all 65-year-old American women can expect to live past age 86, according to Social Security estimates. The average life expectancy for U.S. men who are currently 65 is age 84. The report is based on about 2,000 households that participated in a long-running University of Michigan study. To calculate ideal filing years, United Income estimated retirees’ spending and longevity and ran about 500,000 possible scenarios for each participant, including various market conditions, for a total of about 1.1 billion simulations.