The guidelines issued by the EEOC include the following list of unacceptable questions:
When do you plan on retiring?
Arrest Records: Do not ask questions regarding an applicant’s arrest record. If you are concerned about an applicant’s trustworthiness and it is job-related, you may ask about an applicant’s conviction record.
Disability: It is not appropriate to ask an applicant whether or not they have a particular disability. However, you may ask if the applicant can perform the basic functions of the position.
Emergency Contacts: Do not ask for the name of a relative, instead just simply ask for the name of a person that may be contacted in the event of an emergency.
Gender: No job-related considerations exist that would justify asking an applicant a question based upon gender.
Height/Weight: A company may ask these questions only if they are related to specific job requirements of the position. Otherwise, these questions expose the company to potential claims of national origin discrimination.
National Origin: No job related considerations exist that would justify asking an applicant a question based upon their national origin. However, it is recommended that you should ask if an applicant is legally employable in the United States and may prove it upon request.
Race: No job-related considerations exist that would justify asking an applicant a question based upon race.
Religion: No job-related considerations exist that would justify asking an applicant a question based upon religion. If a concern exists about religious obligations that may restrict the availability to work on certain days or times, then you may ask "Are there any times you are unavailable to work?"
Sexual Preference: Federal law does not address the issue of sexual preference. However some state and local laws do consider sexual preference a protected class. Therefore, in those particular locations there are no permissible questions regarding an applicant's sexual preferences.