(c) Application of rules to other individuals. Any individual who for compensation prepares, or assists in the preparation of, all or a substantial portion of a document pertaining to any taxpayer's tax liability for submission to the Internal Revenue Service is subject to the duties and restrictions relating to practice in subpart B, as well as subject to the sanctions for violation of the regulations in subpart C. Unless otherwise a practitioner, however, an individual may not for compensation prepare, or assist in the preparation of, all or substantially all of a tax return or claim for refund, or sign tax returns and claims for refund. For purposes of this paragraph, an individual described in
26 CFR 301.7701-15(f) is not treated as having prepared all or a substantial portion of the document by reason of such assistance.