Contract Modification
A contract modification is any written change to the terms of an existing contract, executed on Standard Form 30 under FAR Part 43. Bilateral modifications (supplemental agreements) are signed by both parties; unilateral modifications, such as administrative changes and change orders, are signed only by the contracting officer.
Only a contracting officer acting within their authority may execute a modification; FAR 43.102 bars other government personnel from directing or encouraging work that should be the subject of one. Bilateral mods cover negotiated equitable adjustments, definitized letter contracts, and any change both parties agree to. Unilateral mods cover administrative changes, change orders under the applicable Changes clause (52.243-1 through 52.243-5), changes authorized by other clauses such as options, and termination notices.
A change order obligates the contractor to keep performing as changed while the equitable adjustment is negotiated, and 43.204 tells the government to definitize in the shortest practicable time. Mods should be priced before execution; when time will not allow it, at least a ceiling price is negotiated.
Scope is the boundary that matters. GAO treats a modification materially different from the contract originally competed as a new procurement subject to CICA — the test asks whether the field of competition would change and whether the original solicitation put offerors on notice.
Regulatory Reference
FAR Part 43; FAR 52.243-1 through 52.243-5; FAR 43.301 (SF 30)
RFO Status
The Part 43 model deviation, adopted by agencies through class deviations since June 2025, trims non-statutory text but keeps the structure — the unilateral/bilateral split, SF 30, and change-order definitization survive — and Part 43 is not in the June 2026 first-batch proposed rules.
Category
Processes & Methods
How AcqBot Helps
AcqBot drafts the SF 30 package, flags whether a proposed change stays inside the scope of the original competition or needs a new competitive action, and tracks unpriced change orders so definitization does not slide.
Related glossary entries
Sources Sought Notice
A Sources Sought Notice is a pre-solicitation announcement, typically posted to SAM.gov, asking companies to identify their interest and capability to perform a prospective requirement — primarily used as market research to shape competition and set-aside decisions.
Request for Information (RFI)
A Request for Information (RFI) is a formal market research instrument used to gather industry input on capabilities, approaches, pricing structures, or draft requirements when the government is not yet ready to solicit — responses are voluntary and non-binding.
Lowest Price Technically Acceptable (LPTA)
Lowest Price Technically Acceptable (LPTA) is a source selection process that awards to the lowest-priced offeror whose proposal meets minimum acceptability standards — no credit is given for exceeding requirements, and tradeoffs between price and quality are not permitted.
Best-Value Tradeoff
The best-value tradeoff process permits award to other than the lowest-priced or highest-rated offeror when the source selection authority documents that the superior proposal's benefits are worth its price premium, or that a cheaper proposal's savings outweigh its weaknesses.