Hi Larry,
My wife will be turning 66 year in November 2017. She received a letter from Social Security Administration that she is entitled additional income in the form of Supplemental Security Income (SSI).

We wonder what is this and when is the best time to start taking. Does it have any positive effects on spousal benefits? Looking forward to your suggestions.

Hi,

Supplemental Security Income (SSI) is a needs based benefit administered by Social Security but not funded by Social Security taxes (https://www.ssa.gov/ssi/). If your wife qualifies for SSI she would likely want to claim it as soon as possible since she wouldn't gain anything by waiting, and SSI benefits can't be claimed retroactively. Drawing SSI would have no adverse effect on your wife's Social Security benefits. It's simply supplemental income that can be paid to people who qualify.

Best, Jerry