General rules. (1) Any participant, or any person who has filed a timely motion to intervene which has not been denied, may seek to modify its pleading by filing an amendment which conforms to the requirements applicable to the pleading to be amended.

A tariff or rate filing may be amended or modified only as provided in the regulations under this chapter. A tariff or rate filing may not be amended, except as allowed by statute. The procedures provided in this section do not apply to amendment of tariff or rate filings.

If a written amendment is filed in a proceeding, or part of a proceeding, that is not set for hearing under subpart E, the amendment becomes effective as an amendment on the date filed.

If a written amendment is filed in a proceeding, or part of a proceeding, which is set for hearing under subpart E, that amendment is effective on the date filed only if the amendment is filed more than five days before the earlier of either the first prehearing conference or the first day of evidentiary hearings.

If, in a proceeding, or part of a proceeding, that is set for hearing under subpart E, a written amendment is filed after the time for filing provided under paragraph (a)(3)(ii) of this section, or if an oral amendment is made to a presiding officer during a hearing or conference, the amendment becomes effective as an amendment only as provided under paragraph (d) of this section.

Answers. Any participant, or any person who has filed a timely motion to intervene which has not been denied, may answer a written or oral amendment in accordance with Rule 213.

Motion opposing an amendment. Any participant, or any person who has filed a timely motion to intervene which has not been denied, may file a motion opposing the acceptance of any amendment, other than an amendment under paragraph (a)(3)(i) of this section, not later than 15 days after the filing of the amendment.

Acceptance of amendments. (1) An amendment becomes effective as an amendment at the end of 15 days from the date of filing, if no motion in opposition to the acceptance of an amendment under paragraph (a)(3)(iii) of this section is filed within the 15 day period.

If a motion in opposition to the acceptance of an amendment is filed within 15 days after the filing of the amendment, the amendment becomes effective as an amendment on the twentieth day after the filing of the amendment, except to the extent that the decisional authority, before such date, issues an order rejecting the amendment, wholly or in part, for good cause.

Directed amendments. A decisional authority, on motion or otherwise, may direct any participant, or any person seeking to be a party, to file a written amendment to amplify, clarify, or technically correct a pleading.