Do I apply for an NPI as an individual or group/organization?

If you practice as a sole proprietorship, you must apply as a type I (individual). You will have to submit your social security number rather than your employer identification number (even if you have one).

Eligible organizations, including S corporations, may apply for an NPI as an entity Type II (organization). Eligible individuals working within an organization, including an S corporation, may also apply for an NPI as an entity Type I (individual). An S corporation representing only one practitioner is still eligible for a Type II NPI. From an NPI perspective, an S corporation is no different than a limited liability corporation or any other type of corporation.