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FAR and DFARS › FAR Part 43: Contract Modifications › Subpart 43.1

FAR 43.103 Types of contract modifications.

The codified text (eCFR, as of 2026-10-02). Under the Revolutionary FAR Overhaul ↗, agencies follow class deviations with new text for many parts while the formal rules go through the Federal Register: check the solicitation and your contract's clauses, which rule.

In plain English

This section lists the two types of contract modifications: bilateral, which both the contractor and the contracting officer sign, and unilateral, which only the contracting officer signs. It matters because it tells contractors when their signature is required and when the government can change the contract without it.

Applies to: Contractors with federal contracts that may be modified

Key terms: bilateral modification · unilateral modification · supplemental agreement · change order · letter contract

Written by AI from this section's text. A guide, not legal advice: the text below rules.

The text

Contract modifications are of the following types:

(a) Bilateral. A bilateral modification (supplemental agreement) is a contract modification that is signed by the contractor and the contracting officer. Bilateral modifications are used to—

(1) Make negotiated equitable adjustments resulting from the issuance of a change order;

(2) Definitize letter contracts; and

(3) Reflect other agreements of the parties modifying the terms of contracts.

(b) Unilateral. A unilateral modification is a contract modification that is signed only by the contracting officer. Unilateral modifications are used, for example, to—

(1) Make administrative changes;

(2) Issue change orders;

(3) Make changes authorized by clauses other than a changes clause (e.g., Property clause, Options clause, or Suspension of Work clause); and

(4) Issue termination notices.

Sections that refer to it

← 43.102 Policy. · 43.104 Notification of contract changes. →

Rule changes for FAR Part 43

Source: eCFR, 48 CFR chapters 1 and 2 (GPO GovInfo bulk data) ↗. Plain words for the terms: glossary.

FAR 43.103 Types of contract modifications · SpendQuery