The SSN FAQ has now been broken up into several sections. This
section covers "actual FAQs"; that is, it responds to the questions that
are most frequently asked of me.
The short answer is that there are many restrictions on government agencies asking for your number, but few on individuals or companies. When someone from a government agency asks for your number, they are required to provide a Privacy Act Disclosure Notice, which is required to tell you what law allows them to ask, whether you have to provide your number, and what will happen if you don't provide the number.
Private companies aren't required to follow this law, and in general your recourse is to find another company to do business with if you don't like their policies.
There are two problem with the way SSNs are used these days. The first is that they are used (by different parties) as if they were both a representation of identity and a secure password. The second problem is that they have become a widely used identifier which can be used to tie multiple records together about a single individual.
Many institutions, including hospitals and some banks and brokerages use client's SSNs as a secure representation of their identity. This seems a good idea, since you aren't allowed to change your SSN, even though you might change your address, your name, or your phone number. Other institutions, notably banks, use SSNs as if they were secret passwords that only the owner would know. If someone knows the name and the SSN, and is willing to say they have forgotten the account number, they will usually be allowed to transfer funds, or make other changes to an account with serious repercussions.
The problem is that these uses are incompatible. As SSNs are widely used representations of people's identities, appearing on driver's licenses, mailing labels, and publicly-posted progress reports at universities, their broad availability becomes more apparent.
There is further discussion of this issue in the section on Significance of the SSN.
For the first few decades that SSN cards were issued, they carried the admonition: "Not to be used for Identification." Unfortunately there was never any law passed instituting this as a policy. The Social Security Agency was apparently attempting to instill good values in the citizens, but was apparently unsuccessful in preventing government encroachment into this territory. For more information on the evolution of the laws concerning privacy and Social Security additional details are available in the more complete version of the FAQ.
The IRS says US Citizens who receive income are required to have an SSN and employers are required to report income to the IRS using the SSN. The written laws on this point are not very clear, and many people who have read the law feel that the IRS is on shaky legal ground. However, it's quite important to realize that your employer is quite likely to believe the IRS when they say it is required over your claims to have read the law and reached your own conclusions.
There are people who claim, based on nuances of the texts of the laws that these IRS claims are incorrect and illegal. They point to a single court case. As far as I can tell, these claims have not been upheld more recently. The IRS continues to prosecute and harrass those who attempt to resist having their incomes reported. I give pointers to these claims, not because I believe them, but because I can't disprove them. Caveat Lector: the IRS is willing to throw you in jail for violating their interpretation of the laws. They are willing to shoot you for resisting arrest. The have a separate court system, which follows a different set of rules and procedures. Be sure that you understand the potential consequences, and that you are willing to pay the price before you enter this fight.
Seeking agreement and moral support, not all of the people propounding these views will inform you fully of the potential consequences of joining their fight.
As far as I can tell, the SSA doesn't recognize any procedure for renouncing your SSN. The one exception I know of is that a parent who can show that a number was assigned to their child without the parent's consent can get the number removed from the SSA's records.
On the other hand, the SSA has no objection to your not revealing your SSN as long as you do not engage in activities that bring you under some legal compulsion to show it.
You can get a replacement card from the Social Security Administration. Their web site has the necessary forms.
Depending on whether and how quickly you got it back, and whether you suspect someone might have stolen your credit cards, driver's license, or SS Card, different steps are called for. A complete guide is available at the Privacy Rights Clearinghouse.
The SSA doesn't seem to have set policies about issuing new SSNs. As far as I can tell, they will only rarely issue a new SSN to someone who has a significant problem with a stalker or identity theft. In either case, you apparently have to convince someone at the local office that you have tried all reasonable avenues for handling these problems, and the problem continues to reappear because someone is tracking you through your SSN, or because the identity thief continues to create new false credit reports via misuse of your SSN.
There are quite a few companies offering to get you a new SSN to help you escape credit problems. I haven't dealt with any of them, so I can't report on this from personal experience, but I would be surprised if any of them are doing anything that is both legal and valuable. The only legal way to get a new number is to talk to the SSA, and they are reluctant enough to issue a new number that you would have to deal with them directly in order to legally get a new number. Another ploy apparently used by these companies is to apply for a new number, make one up for you, or apply for an employer's Tax ID number. All of these are fraudulent, and unlikely to help you.
I would expect many of the people making these offers to be pure con artists who would take your money, and not provide any service at all. Since the service you are asking them to perform is illegal, they are not very worried that their unsatisfied customers will report them to the police.
A longer discussion and background information on this question can be found here.
This site is about Privacy. I recommend contacting a Private Investigator if you want to trace someone. Sometimes it helps to have an SSN, but the number isn't magic.
This site is about Privacy and Social Security Numbers. The Social Security Administration has a website where they have forms for practically everything. They have their own FAQs, and these are both likely to be found there.
In addition, you can reach the SSA by phone. They're in the government section of every local phone book in the US.
The details are available in this long description. The first three digits reflect the location of the residence given on the application for an SSN. They used to depend only on the SSA office that issued the number. The SSA regularly publishes tables showing the latest numbers being issued for each area.
There is a persistent rumor that the SSA encodes ethnicity in the middle two digits. Most people have an even number as their fifth digit, independent of ethnicity. This is because these numbers are handed out in a strange sequence, and most regions of the country haven't reached the odd numbers yet.
If you have suggestions for improving this document please send them to me firstname.lastname@example.org.