Social Security is an earned benefit. You become eligible by paying the payroll tax during your working years, and the amount you get is geared to your wage history - with a glaring exception.

Social Security has a big birthday coming up next year -- it's turning 90! It's kept many millions of people out of poverty for decades and was recently supporting more than 71 million people with around $1.5 trillion in benefits for the year.

If you were planning to retire next year, double check your math because a law passed in the ’80s is annually raising the age when Americans can collect their full Social Security benefits. And next year is no exception.