AIA Contract Series · ARE 5.0 Exam Prep · Updated May 2026
AIA C401 explained for ARE 5.0
A plain-language breakdown of the Architect-Consultant Agreement — what it covers, how it structures the relationship between architect and consultant, and why it matters for your exam.
What is AIA C401?
The AIA C401 — formally titled Standard Form of Agreement Between Architect and Consultant — is the contract that governs the relationship between the architect and their subconsultants, such as structural engineers, mechanical engineers, or other specialists hired to assist on a project. The 2017 edition is the version tested on the ARE 5.0.
While B101 defines the relationship between the owner and architect, C401 flows down from that agreement. The architect becomes the prime professional, and the consultant works under the architect’s direction. C401 mirrors many of the same obligations the architect has to the owner — but applies them between the architect and their consultant.
Why C401 appears on CE, PjM and PcM
C401 is tested across all three divisions because it governs the full lifecycle of the consultant relationship — from how a firm structures agreements to how the architect manages consultants during construction. Here is how each division connects to it:
CE
Construction & Evaluation
Covers how the architect coordinates consultants during construction administration, manages consultant submittals, and handles disputes between consultants and the contractor.
PjM
Project Management
Covers how the architect manages consultant scope, schedule, and deliverables throughout the project, and how changes to the work affect consultant compensation.
PcM
Practice Management
Covers how firms structure consultant agreements, allocate liability, address insurance requirements, and flow down obligations from the prime agreement.
Key concepts to know for the exam
Flow-down provisions
The prime agreement governs
To the extent applicable, the consultant assumes toward the architect the same obligations the architect assumes toward the owner under the Prime Agreement. This creates a flow-down structure where responsibilities cascade through the contract chain — the owner sets expectations for the architect, and the architect passes those obligations to the consultant. This structure means the consultant is indirectly bound to the owner’s requirements through the architect, to the extent applicable. This flow-down structure is critical for liability — the architect is responsible to the owner, and the consultant is responsible to the architect.
Flow-down responsibility chain
The consultant’s responsibilities mirror the architect’s obligations to the owner, to the extent applicable. The architect is liable to the owner; the consultant is liable to the architect. No direct liability exists between the consultant and the owner.
Scope of services
Limited to this portion of the project
The consultant’s scope is defined in the agreement and limited to “This Portion of the Project.” The consultant performs only the services listed. The consultant shall not proceed with Additional Services without written authorization from the Architect — even if the additional work is requested by the contractor or owner directly. This is a frequently tested exam trap.
Compensation
Paid through the architect
The consultant is paid by the architect, not directly by the owner. Payments are typically aligned with the architect’s receipt of payment from the owner, but the architect remains responsible for compensating the consultant in accordance with the agreement. C401 specifies the payment method — stipulated sum, percentage of construction cost, or hourly rate.
Instruments of service
Who owns the consultant’s work?
The consultant retains ownership of their instruments of service, just as the architect does under B101. The architect receives a license to use the consultant’s work for the specific project only. This mirrors the B101 ownership structure exactly.
Insurance
Consultant must carry coverage
C401 requires the consultant to maintain insurance as specified in the agreement, typically including professional liability, general liability, and workers’ compensation. The consultant’s insurance requirements must be coordinated with the architect’s obligations under the Prime Agreement. The architect is typically named as an additional insured on the consultant’s general liability policy, where applicable.
Dispute resolution
Follows the prime agreement or C401 procedures
Disputes between the architect and consultant follow C401 procedures. When disputes relate to the owner or project issues under the Prime Agreement, the architect typically manages and passes those issues through the contract chain. The consultant has no direct contractual relationship with the Owner and typically pursues claims through the Architect.
Common exam traps
- To the extent applicable, the consultant assumes the same obligations toward the architect that the architect assumes toward the owner — the flow-down structure is one of the most tested C401 concepts.
- The consultant is paid by the architect, not the owner — there is no direct contract between the consultant and owner. The architect remains responsible for compensating the consultant in accordance with the agreement.
- The consultant retains ownership of their instruments of service — the architect only receives a license to use them for the specific project.
- The consultant shall not proceed with Additional Services without written authorization from the Architect — even if requested directly by the contractor or owner.
- The consultant typically communicates through the architect and does not communicate directly with the owner unless authorized by the architect.
- C401 is a subconsultant agreement — it is not used between the owner and a specialist hired directly by the owner.
- The consultant has no direct contractual relationship with the owner and typically pursues any claims through the Architect.
Exam tip
When an ARE question describes a dispute or payment issue between the architect and a structural or MEP engineer, that relationship is governed by C401. The key question to ask is: who hired this consultant? If the architect hired them, C401 applies. If the owner hired them directly, C401 does not apply and the owner has a separate agreement with that consultant.
How C401 relates to other AIA contracts
C401 sits directly below B101 in the AIA contract hierarchy. B101 governs the owner-architect relationship, and C401 governs the architect-consultant relationship. The obligations flow downward: the owner sets expectations for the architect in B101, and the architect passes those obligations to the consultant in C401. Understanding this hierarchy — owner → architect → consultant — is essential for answering contract questions across CE, PjM and PcM.