Construction costs rarely stay exactly where they start. Material prices fluctuate, project scope evolves, and unforeseen conditions can affect both schedule and budget. A guaranteed maximum price (GMP) contract helps owners establish a cost ceiling while giving contractors the flexibility of a cost-plus payment structure.
A GMP contract sets the maximum amount the owner will pay for the cost of the work plus the contractor’s fee, subject to approved changes and the terms of the agreement.
For owners, a GMP can reduce cost uncertainty while preserving the transparency of a cost-plus arrangement. For contractors, it creates a strong incentive to manage costs, schedule, and scope carefully.
Like any payment method, a GMP structure works best when both parties clearly define the scope, document any assumptions, and understand how things like change orders, contingencies, and shared savings affect the final contract price.
Build smart by understanding when a GMP is the right choice, how it differs from other payment methods, and which AIA contract documents support GMP projects.
Quick Decision Guide: Which Agreement Fits Your Project?
If your project… | Recommended Agreement |
Needs a guaranteed cost ceiling between an owner and contractor | A102™ – Agreement Between Owner and Contractor, Cost Plus Fee with Guaranteed Maximum Price |
Uses a construction manager as constructor (CMc) with a GMP | |
Uses cost-plus payment without a maximum price | A103™ – Agreement Between Owner and Contractor, Cost Plus Fee Without Guaranteed Maximum Price |
What Is a Guaranteed Maximum Price (GMP) Contract?
A GMP contract is a type of cost-plus agreement that establishes a price cap the owner will pay for the cost of the work, plus the contractor’s fee. The owner reimburses the contractor for the actual allowable costs, but only up to the guaranteed maximum price, unless the contract allows for adjustments.
Unlike a fixed-price contract, a GMP contract provides visibility into the actual reimbursable costs because the contractor’s payment is based on documented reimbursable expenses rather than a predetermined lump sum.
If the final project cost is less than the GMP, the contract should include a savings provision that explains how the remaining amount is distributed.
How GMP Contracts Work
A GMP contract combines the transparency of cost-plus compensation with the predictability of a maximum price. Instead of agreeing to one fixed contract amount, the parties establish a spending limit while documenting how project costs will be tracked and reimbursed.
A GMP contract generally establishes:
- The estimated cost of the work
- The contractor’s fee
- The guaranteed maximum price
- Allowances
- Contingencies
- Assumptions used to establish the GMP
The agreement also explains how the project will be administered, including:
- Cost reporting requirements
- Payment processes
- Change order procedures
- Documentation requirements
- Shared savings provisions, if applicable
- The records the contractor must maintain to support payment applications
The GMP is typically agreed to between the owner and construction manager (or contractor) before the design team has completed its construction documents. Because the GMP is based on an incomplete design, it should incorporate assumptions, allowances, contingencies, and other pricing qualifications to address elements of the work that are not yet fully defined.
The GMP is not necessarily fixed for the price of the project; it may increase or decrease if the owner approves changes to the work through change orders, or if the agreement allows other specific adjustments. Because of that, the GMP should always be supported by clearly defined scope, assumptions, exclusions, and documentation requirements.
GMP Contracts From the Contractor’s Perspective: Risks and Rewards
A GMP contract allows contractors to provide owners greater cost certainty while still being reimbursed for actual project costs. At the same time, it transfers significant financial responsibility and meaningful risk to the contractor.
If actual reimbursable costs exceed the GMP, and the overrun is not covered by an approved change or other contract adjustment, the contractor is generally responsible for the additional costs. Because of that risk, successful GMP projects depend on disciplined estimating, waiting for the design to reach a suitable level of development before agreeing to the GMP, subcontractor buyout, contingency planning, and ongoing cost tracking.
Why Contractors Choose GMP Contracts
For contractors, a GMP can provide several important advantages:
- Stronger Owner Confidence: A GMP gives owners greater cost certainty, making proposals more competitive.
- Clear Cost-Control Incentives: The contractor has a direct reason to manage labor, materials, subcontractors, and schedule carefully. Costs saved below the GMP can improve profitability, depending on how the agreement handles savings.
- Project Savings: Some GMP agreements include a savings provision that may reward the contractor for finishing below the GMP.
- Improved Documentation and Project Controls: GMP projects typically require detailed documentation, which can support cleaner payment and closeout workflows.
The trade-off is margin risk. Contractors should establish a GMP only after the project scope, assumptions, exclusions, and pricing risks have been sufficiently developed to estimate the work with confidence.
GMP Contracts From the Owner’s Perspective: Cost Certainty and Transparency
For owners, a GMP contract balances budget protection with cost transparency. Instead of paying a predetermined lump sum, owners reimburse actual project costs while knowing those costs cannot exceed the GMP unless the contract allows an adjustment.
That combination makes GMP contracts attractive for projects where the design is substantially developed, but the parties still benefit from collaborative cost management during construction.
Why Owners Choose GMP Contracts
Owners often select a GMP because it provides:
- Greater budget certainty than traditional cost-plus contracts
- Visibility into actual project costs
- Incentives for contractors to manage costs efficiently
- Flexibility when project scope continues to evolve
- Early contractor involvement
- Using a GMP feature with a construction manager delivery method allows the owner to bring the CM on the project earlier to benefit from their construction expertise during design.
Unlike a fixed-price agreement, owners can see how project funds are being spent throughout construction, giving them greater confidence in payment decisions.
Why Documentation Matters for Owners
Strong records are what make a GMP work for the owner because payment is based on documented costs. Detailed documentation helps owners:
- Verify reimbursable costs
- Review payment applications
- Understand GMP adjustments
- Maintain a clear audit trail
- Reduce payment disputes
For payment applications and continuation sheets on Cost of the Work projects with a GMP, use:
- G702GMP® – Application and Certificate for Payment for Cost of the Work Projects with a Guaranteed Maximum Price
- G703CW® – Continuation Sheet for Cost of the Work Projects
These forms are built to document reimbursable costs against the GMP and simplify payment administration, keeping the audit trail clean.
Cost-Plus, GMP, and Fixed-Price Contracts: Key Differences and When to Use Each
While a GMP is a cost-plus contract, it adds a maximum price that changes how the parties share financial risk. Understanding how each payment method works can help you choose the right agreement for your project.
Cost-Plus Without a GMP
In a traditional cost-plus agreement, the owner reimburses the contractor for the actual cost of the work plus an agreed fee. There is no maximum project cost.
This approach works well when:
- Project scope is uncertain and still evolving
- Pricing the work accurately is difficult
- The owner prioritizes flexibility over budget certainty
Because there is no spending cap, owners take on more financial risk if costs increase during construction. For that reason, owners rarely agree to this method.
Cost-Plus With a GMP
A GMP contract retains the transparency of cost-plus compensation while adding a GMP.
This approach works well when:
- The design is substantially developed
- The owner wants greater cost certainty
- The contractor can confidently estimate the work
- The parties want visibility into actual project costs
A GMP often strikes a balance between flexibility and financial protection.
Fixed-Price Contracts
In a fixed-price contract, the owner pays a set contract amount for the work, subject to approved changes. Payment does not depend on the contractor’s actual costs, so the contractor keeps any savings and absorbs any overruns.
This approach works well when:
- The project scope is well defined
- The design is complete
- The parties want the highest level of cost predictability
Unlike a GMP contract, owners generally do not receive the same visibility into actual project costs because payment is based on the agreed contract amount rather than reimbursable expenses.
AIA Contract Documents for GMP Projects
The right agreement depends on how your project is delivered. Two primary contracts support GMP projects.
A102 for Traditional Owner-Contractor Relationships
A102™ – Agreement Between Owner and Contractor, Cost Plus Fee with Guaranteed Maximum Price is the standard AIA contract document for traditional owner-contractor projects using a GMP. The GMP is established in A102 and adjusted through change orders as the design develops.
A102 is used when:
- The owner contracts directly with the contractor
- The project uses a traditional design-bid-build relationship
- The parties want cost-plus compensation with GMP
The agreement establishes the GMP and provides a coordinated framework for adjusting that amount through approved change orders when the project changes.
A133 for Construction Manager as Constructor (CMc)
A133™ – Agreement Between Owner and Construction Manager as Constructor (CMc) With Guaranteed Maximum Price applies to the construction manager as constructor (CMc) delivery method. This method is by far the most common used in GMP projects.
Unlike a traditional contractor, the CMc is often involved during preconstruction, providing estimating, scheduling, constructability reviews, and budgeting before construction begins.
Because of that early involvement, the GMP is typically established through an amendment after the parties have developed enough design information to price the work accurately.
A133 is used when:
- The project uses a CMc delivery method.
- The construction manager participates during preconstruction.
- The owner wants collaborative budgeting before establishing the GMP.
The primary difference between A102 and A133 is the project relationship. A102 supports a traditional owner-contractor GMP arrangement. A133 supports projects where the construction manager is involved much earlier in the project lifecycle.
Choosing the Right GMP Agreement
A GMP contract can align owners and contractors around cost control, transparency, and efficient project delivery. It works best when the parties clearly define the scope, document assumptions, and establish a process for managing changes throughout construction.
Before selecting a GMP contract, ask a few practical questions:
- Is the project developed enough to establish a realistic maximum price?
- Can the contractor confidently estimate labor, materials, and subcontractor costs?
- Are allowances and contingencies clearly defined?
- Does the agreement explain how shared savings will be distributed?
- Are documentation and payment procedures clearly established?
If the answer to those questions is yes, a GMP can provide both financial predictability and operational flexibility throughout the project.
Build Smart With Coordinated AIA Contract Documents
Choosing the right payment method is only one part of managing construction risk. Using A102 and A133 provides standard, coordinated agreement structures for cost-plus GMP projects.
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Frequently Asked Questions
No. A GMP contract is a cost-plus agreement with a cap. The owner pays reimbursable costs plus the contractor’s fee, up to the guaranteed maximum price. A fixed-price contract uses a set contract amount, subject to approved changes.
Yes. Although a GMP establishes a maximum price, it is not necessarily fixed for the life of the project. Approved change orders, owner-directed scope changes, or other contract provisions may increase or decrease the guaranteed maximum price.
If actual reimbursable costs exceed the GMP, and the overrun is not covered by an approved change or other contract adjustment, the contractor is generally responsible for the additional costs.
If the project costs less than the GMP, the contract determines how the savings are handled. Some agreements return the savings to the owner, while others divide them according to a negotiated provision.
An owner may use a GMP contract when the project scope is developed enough to set a reasonable price cap, but the owner still wants the transparency of cost-based payment.
Documentation supports payment, cost review, change orders, and closeout. GMP contracts depend on clear records because the owner pays based on reimbursable costs, subject to the agreed maximum price.
