As long as you are still working, and don't need the money, it may be beneficial to delay it. Even if your income doesn't go up at all those last few years, your SS benefit increases 8% per year until you turn 70. So if you can wait from 66 to 70, your benefit will be 32% more automatically. It's not the right choice for everyone, but if you are still working or have other income coming in, it might be a good choice. BTW, the full retirement age for full benefits is not 65 anymore. For me, it was 66. Depending on the year you were born, it may be different for you.