{
  "node_id": "us-far-part-43-contract-modifications",
  "title": "FAR Part 43 - Contract Modifications (Bilateral, Unilateral, Change Orders, Constructive Changes)",
  "domain": "Public Sector & Government Procurement",
  "version": "1.0.0",
  "last_updated": "2026-06-01",
  "bluf": "Federal Acquisition Regulation (FAR) Part 43 governs modifications to federal contracts and prescribes the only authorities by which the Government may alter a contract: Subpart 43.1 defines bilateral modifications (signed by both contractor and contracting officer - used for negotiated equitable adjustments, definitization of letter contracts, and other agreements) and unilateral modifications (signed only by contracting officer - used for administrative changes, change orders, and other authorised modifications); FAR 43.102 establishes that only contracting officers with proper authority may execute contract modifications - other Government personnel must not direct contractors to perform work requiring a modification (preventing the constructive change doctrine from being weaponised by uncoordinated agency personnel); 43.103 categorises modifications and 43.201 prescribes change order authority through the standard Changes clauses (52.243-1 fixed-price supplies, 52.243-2 cost-reimbursement, 52.243-3 time-and-materials, 52.243-4 construction with consolidated change procedures); 43.204 requires the contracting officer to negotiate equitable adjustments in the shortest practicable time considering segregable costs and including complete releases to prevent future disputes; 43.205 prescribes the mandatory changes clauses; 43.301 mandates Standard Form 30 (SF 30) for solicitation amendments, change orders, unilateral contract modifications, administrative changes, supplemental agreements, and fund adjustments. Constructive changes - actions by Government personnel that direct work beyond contract scope without a formal modification - give rise to constructive change claims under the Changes clause.",
  "paywall": {
    "status": "LOCKED",
    "unlock_cost_usd": "0.01",
    "skyfire_id": "41779894-ece2-4163-9761-b3b1b76e19b0"
  },
  "crosswalks": {
    "_available_keys": [
      "statutory_basis",
      "modification_types_42.103",
      "industry_mapping",
      "constructive_change_doctrine",
      "changes_clause_taxonomy",
      "equitable_adjustment_components"
    ],
    "_note": "Full crosswalk values included in vault response"
  },
  "dependencies": [
    "us-far-part-33-protests-disputes-appeals",
    "us-far-part-15-contracting-by-negotiation",
    "us-far-part-49-termination-of-contracts",
    "us-far-part-42-contract-administration-audit"
  ],
  "primary_citations_count": 6
}