This seems like a simple, straightforward question, but it is actually more complicated than it sounds. When it comes to your full benefit, it all depends on the year of your birth. For people born in 1954 or earlier, the age of eligibility is 66 under currently existing laws. It then goes up by two months per year, so if you were born in 1955, you become eligible two months after your 66th birthday. This arrangement stops in 1960; people that were born during this year and after become eligible when they are 67 years of age.The above being stated, you do not have to wait until you are eligible for your full benefit to apply for Social Security. When you are as young as 62, you can accept a reduced benefit. The exact amount of the reduction will depend on the year of your birth as well, but it is typically about 25 percent.You can go in the other direction and choose to delay your application for Social Security eligibility beyond the full eligibility age. If you go this route, your benefit will increase by eight percent for every year that you delay. However, this ends when you reach the age of 70.