The law guarantees confidentiality if you make a “protected disclosure” to OSC. However, keep in mind, OSC will generally not consider anonymous disclosures. If a disclosure is filed by an anonymous source, the disclosure will be referred to the SSA OIG. OSC will take no further action on the disclosure.
Similarly, the Inspector General Act prohibits the SSA OIG from disclosing the identity of an employee who reports alleged wrongdoing unless it is unavoidable or is compelled by a court order.
With that said, it is always possible that your identity will be ascertainable by others if an investigation takes place, due to the nature of the allegations, or for other reasons.
Further, there may be circumstances, usually related to litigation, where agencies are compelled to identify whistleblowers, or circumstances where identities must be disclosed for health or safety reasons.