Fixed-Price vs Cost-Plus Contract: Which Is Better for Homeowners in 2026

What Is a Fixed-Price Contract and When Should You Use One?

A fixed-price contract (also called a lump-sum contract) locks the total cost of your project at a single number before a single nail is hammered. You pay that number. If the contractor runs over, that is their problem. If they finish under, they keep the difference.

As a licensed GC who has completed hundreds of remodels, I tell homeowners this: fixed-price contracts are best when the scope of work is completely defined before you sign. Full architectural drawings, finishes selected, every line item specified. The less ambiguity, the better this contract type works for you.

Where fixed-price breaks down is in older homes and gut renovations. When you open up walls in a 1960s house, you will find surprises. Knob-and-tube wiring. Asbestos. Dry rot. A contractor pricing a fixed-price job in that environment will add a buffer of 10 to 15 percent to protect themselves from the unknown. You end up paying for contingency you may not need - and if you do need it, you often still end up paying more via change orders anyway.

"As a contractor, I can tell you that most fixed-price bids on remodels are not actually fixed. The fine print usually allows change orders for anything we could not see before demo. So homeowners think they have price certainty and they do not. Read every exclusion clause before you sign."

What Is a Cost-Plus Contract and What Does the Markup Actually Mean?

A cost-plus contract means you pay the actual cost of materials and labor, plus a markup - the contractor's overhead and profit. That markup is the number that surprises homeowners most, so let me be direct about it: residential GC markups on cost-plus jobs typically run 15 to 25 percent on top of all subcontractor costs, materials, and permits.

There are two flavors of cost-plus: cost-plus percentage (markup scales with total cost) and cost-plus fixed fee (the GC's profit is a flat dollar amount regardless of how much the project costs). If you are going cost-plus, push hard for a fixed fee. When a GC's profit percentage is tied to total spend, they have zero incentive to save you money on materials or sub costs.

Based on typical project data from Bay Area contractors, cost-plus jobs on whole-house remodels in the $300,000 to $800,000 range often come in 12 to 20 percent over the initial budget estimate. That is not fraud - it is just the nature of open-ended scope. The actual costs are real. But "actual costs" covers a lot of ground when you are not watching closely.

"As a contractor, I can tell you that cost-plus gives you full transparency when you demand it. Ask for receipts on everything. Any GC who balks at showing you subcontractor invoices on a cost-plus job is the wrong GC."

Cost-plus works well for complex projects where the scope cannot be fully defined upfront - large additions, phased remodels, custom home builds where you want flexibility to upgrade or change materials as the project progresses.

How Do Fixed-Price and Cost-Plus Contracts Actually Compare?

Here is the side-by-side breakdown every homeowner should read before signing anything.

The honest answer is neither contract type is inherently safer. Both can work in your favor or against you depending on how the contract is written and how clearly the scope is defined. The contract type matters less than the specific language inside it.

Which Contract Type Protects You More From Budget Blowouts?

It depends on one thing: how well-defined is your scope. That is not a dodge - it is the actual answer.

In my experience building homes across Silicon Valley since 2017, the worst budget blowouts I have seen happened on fixed-price contracts where the scope was vague. The homeowner assumed "fixed-price" meant no surprises. The contractor delivered 8 to 12 change orders that ate up the savings they thought they had locked in. One kitchen remodel I reviewed had a $95,000 fixed-price contract that finished at $134,000 after change orders.

For cost-plus to protect you, three things must be in the contract:

• A not-to-exceed (NTE) cap. This is a maximum total budget. Any cost-plus contract without a cap is a blank check. Do not sign it.
• Open-book accounting. You have the right to see every subcontractor invoice and receipt. This is non-negotiable on cost-plus.
• Fixed fee, not percentage markup. The GC's profit should be a flat dollar amount - say $45,000 on a $300,000 project - not 15% of whatever it costs. Percentage markups create the wrong incentives.

For fixed-price to protect you, get a detailed exclusions list. Every item the contractor is NOT including in the fixed price should be spelled out. If the exclusion list is vague - "additional costs for unforeseen conditions" - that clause will swallow your budget.

Add a contingency regardless of which contract type you choose. From working with homeowners on projects ranging from $50,000 to $2M+, the right contingency is 15 to 20 percent. Not 10 percent. Every project hits something. Older homes need 20 percent minimum.

Platforms like Opsite give homeowners a client portal where they can track draws, approve change orders, and see project financials in real time - which is especially valuable on cost-plus projects where watching actual spend against budget matters every week.

What Red Flags Should I Watch for in Each Contract Type?

Red flags are different depending on the contract type. Here is what to look for in each.

Fixed-price red flags:

• The bid is more than 20 to 25 percent below competing bids. That contractor is either planning to make it up in change orders or will go broke mid-project and abandon the job.
• The contract uses the phrase "allowances" for major line items like cabinetry, plumbing fixtures, or tile. Allowances are not fixed prices - they are placeholders. If the actual cost exceeds the allowance, you pay the difference.
• The exclusions list is one line long. Any legitimate fixed-price contract for a remodel should have a half-page to full-page exclusions list. One line means the contractor is planning to use "unforeseen conditions" as a catch-all change order later.
• No draw schedule tied to milestones. A draw schedule is how you control payment on any construction project. Without one, you can end up overpaying early and having no leverage if things go wrong. Read the full draw schedule guide here.

Cost-plus red flags:

• No not-to-exceed cap in the contract. Walk away from any cost-plus contract that has no budget ceiling.
• Percentage markup above 25 percent on residential work. Based on 2026 construction cost data for California, markups above 25 percent on residential projects are above market and a signal to negotiate or look elsewhere.
• Contractor refuses to share subcontractor invoices. On a cost-plus job you are paying actual costs. You have every right to see what "actual" means. According to CSLB complaint data, billing fraud is far more common on cost-plus jobs where homeowners never saw the underlying invoices.
• The contract does not define what counts as a reimbursable cost. Some contractors try to mark up their own truck, tools, and office overhead as direct costs. The contract should define exactly what categories are billable.

Before you sign anything, go to cslb.ca.gov and look up the contractor's license number. Takes 30 seconds. Check that the license is active, the classification matches the work, and there are no disciplinary actions. If anything is off, stop there.

How Do I Negotiate Better Terms on Either Contract Type in 2026?

Get three bids. Minimum. Not two, not one. Three. And make sure you are comparing the same scope - give every bidding contractor the same drawings and specifications so the bids are actually comparable. I wrote a full breakdown of how to compare contractor bids here.

Once you have bids in, here is how to negotiate regardless of contract type:

On fixed-price: Ask the contractor to break out their bid by category - foundation, framing, MEP (mechanical, electrical, plumbing), finishes, site work. A contractor who refuses to break out their lump sum is hiding something. You should know where the money is going even if the total is fixed.

On cost-plus: Negotiate the markup first, then negotiate a not-to-exceed cap at 110 to 115 percent of the initial budget estimate. Push for a cost-sharing incentive - if the project comes in under budget, you and the contractor split the savings 50/50. This one clause aligns incentives and is worth fighting for.

On both contract types, make sure the following are in writing before you sign:

• Payment schedule tied to milestones, not calendar dates
• Change order process - any change must be in writing and signed before work starts
• Lien waiver requirements - contractor delivers conditional lien waivers at each draw, unconditional at project end
• Warranty terms - one year minimum on workmanship is standard in California
• Building permit responsibility - who pulls permits and who is responsible if an inspection fails

"As a contractor, I can tell you the single best thing a homeowner can do before signing any construction contract is spend $300 to $500 having a construction attorney review it. Most homeowners spend $1,000 on a new appliance without thinking twice but skip the $300 contract review on a $200,000 project. That math never made sense to me."

If your contractor is using a platform that gives you a real-time view into draws and change orders - like the homeowner portal built into tools such as Opsite - that transparency is worth asking about before you hire. It costs you nothing and tells you whether your contractor runs an organized operation or keeps everything in their head.

Frequently Asked Questions

Is a fixed-price contract always safer for homeowners?

Not automatically. Fixed-price contracts offer budget certainty only when the scope is fully defined before signing. On remodels - especially in older homes - vague scope leads to change orders that erode any price certainty you thought you had. A fixed-price contract with a weak exclusions list can end up costing more than a well-structured cost-plus contract with a not-to-exceed cap.

What is a typical contractor markup on a cost-plus contract in California in 2026?

Based on 2026 construction cost data for residential projects in California, GC markups on cost-plus contracts typically range from 15 to 25 percent on top of direct costs including subcontractor invoices, materials, and permits. Anything above 25 percent is above market for residential work and worth negotiating.

What is a not-to-exceed cap and should I always demand one on cost-plus?

A not-to-exceed (NTE) cap is a contractual maximum - the project cannot exceed this dollar amount without your written approval. Yes, always demand one on cost-plus. A cost-plus contract without an NTE cap is an open-ended commitment with no ceiling. Set it at 110 to 115 percent of the initial budget estimate and require written change orders for anything beyond that amount.

Can I switch from cost-plus to fixed-price mid-project?

Technically yes, but it is rare and complicated. Once work has started, switching contract types requires both parties to agree on a new total price, which means pricing work that is already partially complete. If you want a different contract structure, negotiate it before you sign the original agreement - not after demo has started.

What should I do if my contractor wants a large upfront deposit under a fixed-price contract?

Under California law, contractors cannot legally demand more than 10 percent of the contract price or $1,000 as a deposit - whichever is lower - on home improvement projects. A contractor demanding 30 to 50 percent upfront on a fixed-price contract is a red flag. Structure payment as milestone-based draws. Only pay for work that has been completed and inspected.

What is the difference between an allowance and a fixed price?

An allowance is a placeholder for a cost that has not been fully specified yet - say, $8,000 for tile. If your actual tile selection costs $12,000, you pay the $4,000 difference as a change order. Allowances are not fixed prices. Before signing, identify every allowance in the contract and make sure you know what it covers. Allowances that are set unrealistically low are a known tactic for underbidding jobs.

How do lien waivers work and why do they matter on construction contracts?

A lien waiver is a document where your contractor and their subcontractors waive their right to file a mechanic's lien against your property in exchange for payment. On any project, you should require a conditional lien waiver before releasing each draw payment, and an unconditional lien waiver at project completion. Without these, a subcontractor your GC stiffed can put a lien on your home even if you paid the GC in full.

Does Opsite help homeowners track costs on construction projects?

Opsite is built primarily for general contractors, but contractors who use Opsite can share a client portal with homeowners that shows project progress, draw approvals, and change order status in real time. If you are a homeowner vetting contractors, it is worth asking whether your GC uses a project management platform - organized contractors run more predictable projects.