Rev. Rul. 55-149

If a return is prepared for a taxpayer by a person(s) or a firm (including partnerships, corporations, etc.), the individual or firm responsible for such preparation shall complete the statement of verification provided on the income return forms in the following manner:

(a) if the person, (or persons) responsible for the preparation of the return is an individual acting in his own capacity, the statement of verification shall be signed by such individual;

(b) if a firm is responsible for the preparation of the return, the statement of verification shall be signed with the firm name. However, if the firm name is stamped or typed, it should be followed by the signature of a person authorized to sign the verification on behalf of the firm. The firm may authorize any officer, member, or employee to sign the verification.

Such verfication is not required if the actual preparation of the return is a regular and usual incident of the employment of one regularly and continuously employed for full time by the person for whom the return is made (such as a clerk, secretary, bookkeeper, etc.)