Social security is not taxable unless your other income is above $34,000.
Hmm, I just looked it up, and it looks like the limit is based on your other income plus half your social security income. For a single person, head of household (or head of houselesshold for a homeless person?), it would be $25,000 this year, so unless he made $50,000 in benefits or had other income, it’s probably tax free.