If you were born January 2, 1943, through January 1, 1955, then your full retirement age for retirement insurance benefits is 66.
If you work and are full retirement age or older, you may keep all of your benefits, no matter how much you earn.
If you are younger than full retirement age, there is a limit to how much you can earn and still receive full Social Security benefits. If you are younger than full retirement age during all of 2015, the SSA must deduct $1 from your benefits for each $2 you earn above $15,720.
If you reach full retirement age during 2015, the SSA must deduct $1 from your benefits for each $3 you earn above $41,880 until the month you reach full retirement age. Social Security Publication 05-10069 has more information and examples.
See NATP's Social Security Earnings Limits Chart for how much an individual could earn in prior years without a reduction in Social Security benefits.
Note: The reduction above only applies to earned income (e.g., wages and self-employment earnings). Unearned income does not apply to the rules above, however, increased MAGI may increase the cost of Medicare premiums (Social Security Publication 05-10536).