A cost plus contract template is a preformatted construction agreement that lists which project expenses the owner will reimburse and what fee the contractor earns on top. The three templates worth starting from are the AIA A102 (with a price cap), the AIA A103 (without one), and the ConsensusDocs 230. Drafting from scratch is risky because established forms have refined their language over decades, and every vague line in a cost-plus deal turns into a billing dispute later.
Whichever form you start with, the sections that decide whether the contract works in practice are the fee structure, the reimbursable-cost definitions, the exclusions, the change-order procedure, and the owner’s audit rights. Everything below walks through those choices.
Where to Get a Template
AIA A102 and A103
The AIA A102 is the industry-standard template for cost-plus contracts that include a Guaranteed Maximum Price.1The American Institute of Architects. AIA Document A102 – 2017 Standard Form of Agreement Between Owner and Contractor It covers the definition of reimbursable costs, the fee, and how any savings below the GMP get divided. The AIA A103 covers the same ground without a price cap, which fits projects where the scope is too uncertain to set a ceiling. Because the A103 has no cap, it requires the contractor to prepare a Control Estimate and maintain a cost-tracking system so the owner can watch spending in real time.2AIA Contract Documents. A103 Owner-Contractor Agreement – Cost Plus Without GMP Outside of the pricing mechanism, the two forms are structurally similar.
ConsensusDocs 230
ConsensusDocs 230 is a cost-plus-with-GMP agreement developed collaboratively by more than 40 national associations representing owners, contractors, subcontractors, sureties, and design professionals.3ConsensusDocs. Coalition Members Because it reflects input from all sides of the table rather than a single profession, some owners and contractors view its default risk allocation as more balanced than the AIA forms. The template is available for purchase on the ConsensusDocs website.4ConsensusDocs. Owner and Constructor Agreement (Cost of Work Plus a Fee with GMP) – 230
Choose a Fee Structure
The “plus” in cost-plus is the contractor’s compensation for running the job, and the structure you pick shapes the incentives for the entire project. Three models are common.
- Fixed fee. The contractor earns a flat dollar amount regardless of what the project costs. This is the cleanest alignment of interests because the contractor gains nothing from higher spending and has every reason to finish efficiently.
- Percentage fee. The contractor earns a percentage of total project costs. Most residential builders charge between 15% and 20%, though the number can run higher for complex work. The tension is obvious: the contractor’s pay rises as costs rise. Owners who choose this model should pair it with a cost ceiling or frequent audits.
- Incentive fee. The parties agree on a target cost and share savings or overruns according to a formula. If the project finishes under the target, the contractor’s fee increases; if it exceeds the target, the fee shrinks.
Whatever model you pick, the template must state the fee as a specific number or calculation. Vague language like “a reasonable fee” invites litigation. If the fee is a percentage, the contract should also define exactly which cost categories the percentage applies to, since applying it to subcontractor invoices that already include their own markup can inflate the total considerably.
Decide Whether to Include a Guaranteed Maximum Price
A Guaranteed Maximum Price clause, usually called a GMP, sets an absolute ceiling on what the owner will pay. The contractor absorbs any costs above that cap, which shifts meaningful risk back to the builder and gives the owner a worst-case budget number. GMPs appear in everything from mid-size renovations to nine-figure commercial developments.
What happens to the money left over if costs come in below the GMP is a negotiation point the template should address head-on. The AIA A102 divides savings between owner and contractor according to an agreed split, with the owner typically receiving the larger share.1The American Institute of Architects. AIA Document A102 – 2017 Standard Form of Agreement Between Owner and Contractor If the contractor is terminated for cause or walks away before substantial completion, most GMP contracts eliminate the contractor’s share of savings entirely. Failing to address savings distribution in your template is one of the fastest ways to create a dispute at close-out.
Define Reimbursable Costs
The reimbursable-costs section is where most cost-plus disputes are born. This part of the template requires you to list every expense category the owner agrees to pay, line by line. Getting it right means being specific enough that neither party can game the edges.
Standard AIA documents break the Cost of the Work into defined categories: labor (including payroll taxes, workers’ compensation insurance, and fringe benefits), materials and supplies whether incorporated into the project or consumed during construction, equipment rental from the contractor or third parties, bond and insurance premiums tied to the project, and supervision costs directly attributable to the work.5American Institute of Architects. AIA Document A201 – 2017 General Conditions of the Contract for Construction Items that are deliberately excluded, like hand tools, often slip through if the template doesn’t call them out. The same goes for small consumables such as saw blades, sandpaper, and adhesives. If those fall under general overhead the contractor’s fee is supposed to cover, say so explicitly.
For labor, the template should list hourly rates by trade. Skilled trades like electricians and plumbers typically bill at rates well above base wages once insurance, taxes, and overhead are loaded in. Require the contractor to submit verified timecards or electronic time-tracking records with each payment application. For equipment, reference the rental company’s published rate sheet and require daily logs showing when each machine was on site and in use. These details sound tedious at the drafting stage, but they’re what makes the contract auditable.
Spell Out What Won’t Be Reimbursed
Equally important is the list of expenses the owner will not reimburse. Leaving this section vague is an invitation for line items that shouldn’t be there. At minimum, the template should exclude:
- Rework due to contractor error. If the framing crew installs a wall in the wrong location, tearing it out and rebuilding it is on the contractor, not the owner.
- Fines and penalties. OSHA fines, late-delivery penalties from suppliers, and citations for code violations should never land on the owner’s ledger.
- Entertainment and gifts. Dinners, sporting event tickets, and holiday gifts for subcontractors are the contractor’s business expense.
- Costs from the contractor’s other projects. Shared equipment, labor borrowed from another job site, and bulk material orders split across projects require clear allocation rules to prevent double-billing.
The standard AIA and ConsensusDocs forms handle most of these exclusions, but custom additions are common. If your project has unusual characteristics, such as hazardous material abatement or historic preservation requirements, review whether the template’s default exclusions cover the scenarios you’re likely to face.
Address Discounts and Rebates
Contractors frequently receive trade discounts, volume rebates, and early-payment discounts from suppliers. Under the AIA cost-plus forms, those savings belong to the owner. The contract language goes further: the contractor is required to make reasonable efforts to obtain available discounts, meaning a contractor who ignores a supplier’s volume pricing may be in breach.
Cash discounts for early payment have a narrower rule. They go to the owner only if the owner had already funded the payment through a progress billing or deposited money with the contractor specifically for that invoice. If the contractor pays a supplier early using their own cash flow, the contractor keeps the discount. Your template should spell out this distinction, because it determines who benefits from prompt payment on the job.
Build a Schedule of Values
The schedule of values breaks the total project into component parts, each with an estimated cost. It serves as the backbone for progress payments: when the contractor submits a payment application, the owner checks the claimed work against the schedule to verify the request matches reality. In a GMP contract, the schedule also functions as a control against front-loading, where a contractor bills heavily in early phases and leaves the owner exposed if the relationship falls apart mid-project.
Fill out the schedule with enough granularity that each line item represents a meaningful chunk of work, not an entire phase. “Framing, $85,000” is better than “Structural Work, $200,000.” The more detailed the breakdown, the easier it is to spot problems before they compound. Pair the schedule with a requirement that each payment application include backup documentation: supplier invoices, delivery receipts, and subcontractor billing matched to the line items being claimed.
Set Up Change-Order Procedures
In a fixed-price contract, a change order adjusts a known total. In a cost-plus contract, the mechanics are different because the total is already open-ended. What a change order does here is modify the scope, adjust the GMP if one exists, and reset schedule milestones. Without a formal change-order process, scope creep becomes invisible until the final invoice arrives.
Your template should require every change to be documented in writing before the work begins, with a description of what’s changing, an estimate of the cost impact, the effect on the project timeline, and signatures from authorized representatives on both sides. This sounds obvious, but in practice, verbal approvals on a job site are the norm. The contractor adds two outlets, the plumber reroutes a line, and nobody writes it down until the owner sees the bill. A well-drafted change-order clause makes the written approval a condition of reimbursement, so the contractor has a financial incentive to get it on paper.
Include Audit Rights and Record Retention
The owner’s right to examine the contractor’s books is the single most important protection in a cost-plus contract. Without it, the entire reimbursement model runs on trust alone. Standard AIA documents give the owner and their auditor access during regular business hours, upon reasonable notice, to the contractor’s financial records, subcontractor agreements, purchase orders, and any other documentation supporting the costs charged to the project.1The American Institute of Architects. AIA Document A102 – 2017 Standard Form of Agreement Between Owner and Contractor
The template should address three things: when audits can happen (during the project, after completion, or both), what records the contractor must keep, and how long those records must be preserved. The standard AIA retention period is three years after final payment. If your project involves government funding or a public entity, longer retention requirements may apply by law. Don’t rely on the default. Include a specific retention period in the contract and require the contractor to store records in a format that’s accessible for review, whether physical files or cloud-based accounting software with export capabilities.
Sign and Execute the Agreement
Once every section is complete and both sides agree on the terms, execution is straightforward. Authorized representatives from both the contractor and the owner sign the document. “Authorized” matters here: a project manager who lacks signature authority can create enforceability problems. Confirm that whoever signs has the legal authority to bind their organization, whether that means checking corporate bylaws, an LLC operating agreement, or simply confirming that the individual owner is the one holding the pen.
The contract should include a specific commencement date rather than vague language like “upon completion of permitting.” The commencement date establishes when the timeline for milestones and completion begins to run, and an ambiguous start date makes every downstream deadline harder to enforce.6AIA Contract Documents. Notice to Proceed in Construction – A101 Start Date Construction contracts do not require notarization to be legally binding. Some parties choose to notarize anyway, but it’s a preference, not a legal requirement.
After signing, distribute fully executed copies to every stakeholder: the owner, the contractor, the architect or design professional, and any lender providing construction financing. From that point forward, every receipt, payroll record, subcontractor invoice, and equipment log feeds the audit trail that makes the entire cost-plus structure work. If the documentation discipline breaks down, so does the owner’s ability to verify what they’re paying for.