Every federal contractor eventually eats a change order the government won't paper or a delay it won't own. The Contract Disputes Act is the sequence that turns those into recoverable claims — if each step is taken in form.
Contemporaneous records: the daily reports, the emails directing the change, the cost segregation kept from the first disrupted week. Claims assembled from memory a year later negotiate poorly and try worse. The best claims work starts while the problem is still happening — which is also when notice clauses with their own short fuses get satisfied or blown.
Posture and consequences: the REA invites negotiation; the claim starts interest, triggers decision deadlines, and hardens positions. Sequencing them is strategy, not paperwork.
The CDA sets decision timelines, and silence past them becomes a deemed denial — appealable immediately. Stalling loses its power the day you treat the silence as the decision it legally is.
False certifications carry real exposure, which is the point — certified claims are built on support, not hope. Done right, certification is what makes the government take the number seriously.