14 CFR § 61.123 - Eligibility requirements: General.
To be eligible for a commercial pilot certificate, a person must:
(a) Be at least 18 years of age;
(b) Be able to read, speak, write, and understand the English language. If the applicant is unable to meet one of these requirements due to medical reasons, then the Administrator may place such operating limitations on that applicant's pilot certificate as are necessary for the safe operation of the aircraft.
(c) Receive a logbook endorsement from an authorized instructor who:
(1) Conducted the required ground training or reviewed the person's home study on the aeronautical knowledge areas listed in § 61.125 of this part that apply to the aircraft category and class rating sought; and
(e) Receive the required training and a logbook endorsement from an authorized instructor who:
(h) Hold at least a private pilot certificate issued under this part or meet the requirements of § 61.73; and