Responsiveness is about the bid itself: did you bid the work as specified, on the right form, with the bid security, addenda acknowledgments, and certifications attached? Miss a material item and the agency must reject the bid, even if your price is lowest. Responsiveness is judged at bid opening. There is no second chance to cure a substantive defect.
The line between a fatal defect and a waivable one turns on materiality. A missing bid bond or a changed price goes to the substance of the offer and cannot be fixed after opening. A trivial irregularity (an obvious typo or a missing page number) can often be waived as a minor informality. Bidders should not count on that grace, since the call rests with the agency. Nonlinear reads the documents and assembles a checklist of every required submission item, so a forgotten form or unacknowledged addendum does not disqualify an otherwise winning bid.
