23 CFR § 636.409
Can offerors revise their proposals during communications?
May 21, 2020
(a) No, communications shall not provide an opportunity for an offeror to revise its proposal, but may address the following:
(1) Ambiguities in the proposal or other concerns (e.g., perceived deficiencies, weaknesses, errors, omissions, or mistakes); and
(2) Information relating to relevant past performance.
(b) Communications must address adverse past performance information to which the offeror has not previously had an opportunity to comment.