If you are under the full retirement age (in my case, 66), collecting SS and still working, once your work income level hits a certain dollar amount you have to pay back the SS you received.
I was 66 in January. I started collecting benefits. I did not quit working. I may work another few years. 85% of my SS is taxable. I am not on Medicare Part B. I still have my work insurance. My SS monthly check is quite a lot and I’m happy with it. With my 401K and other investments, I should make at least what I’m making now.