3-month trip to California - Do I give my bank my Social Security Number? [closed]

While you should not expose your Social Security Number (SSN) unnecessarily (as it, along with other information about you, can be used to commit identity theft), various people do need it from you, including:

• The government. Especially the Internal Revenue Service (IRS) (the federal tax agency), and state tax agencies.
• Financial institutions. It is used to verify your identity and for compliance with banking laws. If they do not have your SSN, they may be required to withhold extra money for taxes (backup withholding).
• Anybody running a credit check on you, such as if you applying for a credit card, applying for certain jobs, and sometimes even renting an apartment (this should not happen without your permission, but it is a requirement with some landlords).
• Employers. This is to report the wages you earn to the government for tax purposes.

In any such case, you should be careful to ensure you are dealing with a reputable, official organization and not a scam. It is unfortunate that you sometimes must give your SSN to people you don't necessarily trust to keep it secure (prospective employers and landlords especially), but that's the reality of the system at this point, and there's generally not much of an alternative.