Contracts

What is a cost-plus contract in construction?

A cost-plus contract pays the contractor for the actual cost of the work plus a fee for overhead and profit, either a percentage of cost or a fixed amount, instead of a single fixed price.

An office manager and contractor review invoices with a calculator and laptop in a construction office.
Review invoices, committed costs, and cash timing together before making project decisions. AI-generated illustration.

Under a cost-plus contract, the owner pays what the job actually costs, plus the contractor's fee. Labor, materials, subs, and equipment are billed at cost with receipts. The fee covers home office overhead and profit. The owner takes on the risk that the job costs more than expected; the contractor takes on the work of proving every cost.

Owners choose cost-plus when the scope is not fully defined, when speed matters more than a fixed number, or when they trust the builder and want open books. It is common on custom homes, fast-track commercial work, emergency repairs, and as the base of most GMP contracts.

Types of cost-plus contracts

  • Cost plus percentage: fee is a percentage of cost (for example, cost plus 15 percent).
  • Cost plus fixed fee: fee is a set dollar amount regardless of cost. See cost-plus fixed fee.
  • Cost plus fee with a GMP: costs plus fee up to a ceiling; overruns above it are the contractor's.
  • Cost plus incentive fee: fee adjusts based on cost or schedule targets.

How cost-plus works on a real job

Say a builder takes on a custom home with an estimated cost of $900,000 under a cost plus 12 percent contract. The owner keeps changing finishes. Final costs come in at $1,020,000.

Cost plus 12 percent example
ItemEstimateFinal
Cost of the work$900,000$1,020,000
Fee (12 percent)$108,000$122,400
Total paid by owner$1,008,000$1,142,400

Under a percentage fee, the builder earns more as costs grow, which is exactly why some owners distrust it. Under a fixed fee of $108,000, the builder would earn the same fee whether the house cost $900,000 or $1,020,000, unless the contract allowed fee adjustments for owner changes.

Cost-plus on federal work

Federal contracts treat this differently. The Federal Acquisition Regulation says the cost-plus-a-percentage-of-cost system of contracting shall not be used, and other contract types must include a clause barring cost-plus-percentage-of-cost subcontracts. For construction, the FAR says firm-fixed-price contracts should generally be used. Cost-plus-fixed-fee and other cost-reimbursement types exist but come with their own rules.

Common disputes

  1. What counts as cost: home office staff, small tools, company-owned equipment rates, and warranty work are frequent arguments. Define them in the contract.
  2. Missing backup. Owners can refuse costs without invoices, timecards, or receipts.
  3. Markup on subcontractor markup, and whether the fee applies to change orders.
  4. Audit rights and how long records must be kept.

Related terms

See fixed-price contract, time and materials, open book pricing, and reimbursable expenses. The guide on cost-plus vs fixed-price contracts compares the risk side by side.

Frequently asked questions

Is cost-plus good for contractors?

It lowers the risk of losing money on unknowns, but it caps upside, adds paperwork, and invites owner scrutiny of every cost. It works best with clear definitions of reimbursable cost.

What is a typical cost-plus fee?

Fees vary by market, project type, and risk, and are negotiated. The contract sets the rate, so compare it against your real overhead and target profit.

Can federal construction contracts be cost-plus?

Cost-plus-a-percentage-of-cost is prohibited under FAR 16.102(c). Other cost-reimbursement types exist, but the FAR says firm-fixed-price contracts should generally be used for construction.

What is the difference between cost-plus and time and materials?

T&M bills labor at set hourly rates that already include overhead and profit, plus materials. Cost-plus bills actual costs with a separate fee.

Sources

  1. Acquisition.gov: FAR 16.102, policies on contract types
  2. Acquisition.gov: FAR 36.207, pricing fixed-price construction contracts
Written and edited by

Maurice Francois writes and edits construction operations guides for Smart Business Automator. More from Maurice on the Scaling Legends podcast.

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