identity theft
you don't want to give out your social security number unless you have to. it's required for employment. and since we're happy to employ undocumented aliens at low wages and collect taxes from them and not give them some sort of id of their own... they borrow someone else's. in most cases they don't ruin your credit history. remember these folks are here illegally and want to maintain a low profile so they can escape detection and stay. when you pay social security taxes you earn credits to be paid back later in life. but when the social security computers notice that people are filing tax returns using mismatched names and social security numbers, what do they do? they could find the rightful owner and prosecute the infringer. or they could notify all parties and let them sort it out. but they don't. they just quietly keep the money and don't credit anyone. neat huh? tax return information is sacred. and will not be disclosed to anyone. and apparently the fact that someone else is using your ssn apparently is covered by this blanket of confidentiality. the only way to find out if this is happening to you is to figure out what your credits should be and check them against the form the ss people send you every tax year. but if you think filing taxes is difficult... yeah. let me know how that one works out for you.