You can start to receive Social Security any time between the ages of 62 and 70. For each year you wait beyond age 62, your monthly payments increase. Nevertheless, there are good reasons why some people start Social Security as soon as possible:
Need. If you have no other source of income and you are unable to keep working, you may have little choice except to start Social Security benefits. In this situation, a smaller payment is better than nothing.
Health. People who have serious medical conditions may not live long enough to make it sensible to defer benefits so that they will be larger later. For such individuals, it probably will make sense to begin benefits as soon as possible, and get as many payments as possible.
See also, Social Security Benefits in Federal Retirement at ask.FEDweek.com
Tax deferral. Some retirees rely heavily on their retirement savings accounts such as the TSP and IRAs for income. There are no required minimum distributions until age 70 1/2. Before that age, people can start Social Security benefits for retirement income, thus keep more money in their retirement savings accounts for a longer time, extending tax-deferred buildup.
Note: For those who work after beginning Social Security benefits, there is an earnings test that applies up to age 66, which could substantially reduce your Social Security benefits depending on your earnings. If you think you will want to, or need to, have earned income in your 62-66 years, be sure to take that into account in your decision.