Ed. Code, § 44399.1

(a) The commission shall issue an authorization for an additional subject or for a new teaching credential type to the holder of a valid California multiple subject or single subject teaching credential, or eligible applicant, who has earned certification from the National Board for Professional Teaching Standards in the additional single subject content area or the new multiple subject or single subject teaching credential type.

(b) Notwithstanding subdivision (a), when there is no direct equivalence between the national certification and the California subject or credential type, the commission shall determine the subject or credential type or may require the applicant to qualify for a commission-approved determination of subject matter competence before issuance of the credential or authorization request. An applicant for a multiple subject teaching credential may also be required to qualify for a commission-approved determination of subject matter competence in order to comply with state subject matter requirements.