Retirement Benefits: Monthly Benefit Change Shows $50 Cent Difference Between Benefit and Voluntary Tax

I got a letter from SS stating that my benefit had changed. My gross benefit was shown as well as my voluntary deduction that I requested to help defray my tax liability at the end of the year. There was a fifty cent difference in the amounts. I was shorted fifty cents on my actual net benefit. When I called my local office for an explanation, I was told that Congress passed a bill four years ago that allowed this deduction. I asked what the deduction was for and that person did not know. I did not torture that person being overly inquisitive, but it remains a mystery for me. I am 71 and started collecting SS retirement five years ago at age 66. I never received a letter or any information from SS explaining this fifty cent deduction. The automated voice that answers the phone at the national information phone number says that 50 million people are receiving SS benefits. At fifty cents a pop, that's 25 million dollars. Not a lot of money compared to the trillions that are in the pot, but it seems mysterious. Has anyone else seen this happen or know what I am referring to?

Retirement Benefits: Monthly Benefit Change Shows $50 Cent Difference Between Benefit and Voluntary Tax