The tax is different than the rule about being under age. When you are under retirement age they will actually reduce your checks if you make too much other income.
But SS is always taxable. 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
