They don't actually tax you. They reduce your actual Social Security checks the next year if you earn over the limit. Don't know how winnings factor into that or if it is just based on wages and earned income.
There are 2 different things to know about social security. People get them mixed up all the time.
1. Your actual SS checks
If you are over full retirement age your actual ss checks won't be reduced. Otherwise they will actually reduce your payments if you make too much other income in the prior year. See SS FAQ for working after retirement
https://www.ssa.gov/planners/retire/whileworking.html
2. Income Tax
For any age up to 85% of Social Security becomes taxable when ALL your other income plus 1/2 your social security reaches:
Married Filing Jointly: $32,000
Single or head of household: $25,000
Married Filing Separately: 0
