Should I ever include my social security number on my resume or an application form?

Short answer: No.

Do not place your SSN on your resume. Identity theft is a concern, and you should carefully guard access to this number.

Scammers could ask for SSN as part of a fake job application.

Even an employer with a legitimate need for your SSN (for a background check, for example) should not collect this on an application form.

According to the Society for Human Resource Management (SHRM): It is not unlawful for employers to request an SSN on an application form; however employers should request SSN only when absolutely necessary, such as in conjunction with a background check, completing a W-4, or enrolling an employee into benefits plans. Therefore the SSN should be collected separately from an application form where it will only be seen and accessed when necessary. An application form may be seen by individuals who do not need the SSN. About.com: Social Security Numbers on Job Applications.