A licensed GC explains the real difference between fixed-price and cost-plus contracts - and which one protects you when things go sideways.
What Is the Actual Difference Between a Fixed Price and Cost Plus Contract?
Fixed-price means you agree on a number upfront - say, $180,000 - and that is what you pay, regardless of what the contractor spends. Cost-plus means you pay the contractor's actual costs (materials, labor, subs) plus a markup, typically 15-25%.
Simple in theory. Wildly different in practice.
With a fixed-price contract, the contractor absorbs cost overruns. With cost-plus, you absorb them. That one distinction shapes every decision you will make about your remodel budget, your risk exposure, and your relationship with your GC from day one.
As a licensed GC who has completed hundreds of remodels, I have used both contract types. Neither is universally better. The right choice depends entirely on how well-defined your project is and how much you trust the person you are hiring.
| Factor | Fixed-Price Contract | Cost-Plus Contract |
|---|---|---|
| Budget certainty | High - you know the number upfront | Low - final cost is unknown |
| Who absorbs overruns | Contractor | You (the homeowner) |
| Requires detailed scope | Yes - essential | No - works with loose scope |
| Typical for | Well-defined remodels, new builds with full plans | Complex renovations, historic homes, fast-track projects |
| Transparency | Lower - you see the price, not the breakdown | Higher - you see every receipt |
| Change order risk | Higher - every scope change triggers a CO | Lower - changes just add to the running total |
| Contractor incentive | Finish fast, control costs | Less incentive to cut costs |
When Does a Fixed-Price Contract Actually Protect You?
Fixed-price protects you when your project is fully designed and the scope is locked. Full stop.
If you have architectural drawings, a complete material schedule, and permits pulled or ready, a fixed-price contract is your best friend. The contractor has priced every line item. Their bid is their commitment. If lumber prices spike or they underestimated demo labor, that is their problem - not yours.
Based on 2026 construction cost data, kitchen remodels with complete design packages typically come in within 5-8% of the fixed-price bid when scope stays unchanged. That is the scenario fixed-price was built for.
But here is what contractors will not always tell you: a fixed-price contract only holds if your scope does not change. The moment you say "while you are at it, can we also move that wall" or "I decided I want the wider window," you have triggered a change order. And change orders on fixed-price jobs are where contractors make back their margin.
"As a contractor, I can tell you that a fixed-price bid with loose scope is actually worse for homeowners than a well-structured cost-plus deal. If I am bidding fixed on an unclear scope, I am padding the number to protect myself. You pay for that padding whether or not the surprises materialize."
Red flag: If a contractor gives you a fixed-price bid without asking for complete drawings or walking every inch of the job with you, that bid has fat in it. Budget-padded bids on vague scopes range from 10-20% above realistic cost, based on typical project data from Bay Area contractors.
When Does Cost-Plus Make More Sense for a Homeowner?
Cost-plus makes sense when your project scope is genuinely unknown at the start. Three situations where I recommend it:
1. Older homes with hidden conditions. If your house was built before 1980, there is a real chance you have knob-and-tube wiring, galvanized pipes, asbestos, or foundation issues that will not show up until walls open. On a fixed-price job, those surprises become contentious change orders. On cost-plus, they are just line items you expected.
2. Design-build projects mid-design. If you are still finalizing finishes, layout decisions, or materials when construction starts, cost-plus keeps the project moving without waiting on a rewritten contract for every change.
3. Fast-track projects. Sometimes you need to start demo before drawings are complete. Cost-plus lets you move without locking in a number that will need to change anyway.
The downside is real: without a hard cap, cost-plus projects can run significantly over your mental budget. In my experience building homes across Silicon Valley since 2017, cost-plus projects without a guaranteed maximum price (GMP) clause regularly finish 15-30% above the initial estimate.
That is not fraud. That is the nature of the contract type. But it feels like fraud when you were expecting $250,000 and you get a $325,000 final invoice.
If you go cost-plus, negotiate a Guaranteed Maximum Price clause. This caps your exposure. The contractor still passes actual costs through, but once the total hits the GMP, they absorb anything above it. Getting a GMP takes a cost-plus contract from "unlimited exposure" to something you can actually budget around.
How Do You Protect Yourself Regardless of Which Contract You Sign?
The contract type matters less than what is inside the contract. Here are the non-negotiables for either type.
Draw schedule tied to milestones. Never pay on a calendar basis. Payments should be tied to completed, inspected work - not to dates. A properly structured draw schedule means you never pay for work that has not happened. Standard splits for a kitchen remodel: 10% deposit at signing, then milestone payments tied to demo complete, rough-in inspections passed, cabinets installed, and final walkthrough.
Lien waiver at every payment. Every time you cut a check, get a conditional lien waiver from the GC and any subs who have been on your job. Platforms like Opsite track lien waivers automatically so contractors can document compliance at every payment - ask your GC if they have a system for this. Without lien waivers, a sub your GC stiffed can file a mechanic's lien on your home even though you paid the GC in full. This happens more often than homeowners expect.
CSLB license verification before signing anything. Go to cslb.ca.gov right now and look up their license. Takes 30 seconds. Confirm the license is active, the bond is current, and there are no disciplinary actions. According to CSLB complaint data, unlicensed contractor complaints represent roughly 20% of all cases filed in California. Do not become a statistic.
A defined change order process. Your contract needs to spell out: all changes must be submitted in writing, with a price and homeowner signature, before work begins. Verbal change orders are how projects balloon from $200,000 to $280,000 without a single piece of paper to show for it.
Contingency in your own budget. Add 15-20% on top of whatever you sign. Not 10%. Not "we will figure it out." Every project hits something unexpected. The question is whether you have the cash to handle it without stopping the job.
For more on how to evaluate bids before you even get to the contract stage, see our guide on how to compare contractor bids without getting played.
What Should a Construction Contract Include in 2026?
Whether it is fixed-price or cost-plus, a contract that does not include these elements is not protecting you.
From working with homeowners on projects ranging from $50K to $2M+, the contracts that lead to disputes almost always have at least one of these missing:
- Complete scope of work - not "kitchen remodel" but a line-by-line description of every task, material specification, and allowance item
- Payment schedule tied to milestones, not dates
- Start date and substantial completion date with a liquidated damages clause if they want accountability
- Change order procedure - written, signed, before work begins
- Materials and subcontractor approval rights - you should approve major subs
- Insurance requirements - minimum $1M GL, workers comp, and auto
- Permit responsibility - who pulls them, who pays for them
- Warranty terms - 1 year on labor is standard in California; some GCs offer more
- Lien waiver requirements at each draw
- Dispute resolution process
California law (Business and Professions Code Section 7159) actually requires residential contracts over $500 to include specific elements. A contractor who hands you a one-page "agreement" on a $150,000 kitchen remodel is not just being sloppy - they may be violating state law.
"As a contractor, I can tell you that a homeowner who asks for all of these things is not a difficult client. They are a prepared client. And prepared clients have better projects. Every single time."
What Is a Typical Markup on a Cost-Plus Contract in 2026?
Legitimate GC markup on cost-plus contracts in the Bay Area and greater California market typically runs 15-25% on total project cost, based on 2026 construction cost data.
That markup covers overhead (office, insurance, licensing, project management staff) and profit. On a $300,000 project at 20% markup, you are paying $60,000 for the GC's business overhead and margin. That is a real number, and it is not unreasonable for a licensed, insured, quality contractor running a professional operation.
Be suspicious if a contractor offers cost-plus at 8-10% markup. Either they are hiding costs in inflated invoices, they are not properly insured, or they are not accounting for real overhead. None of those outcomes are good for you.
Ask to see the markup structure in writing. A reputable contractor will show you: "Materials at cost plus 10%, labor at cost plus 15%, sub contracts at cost plus 10%." That breakdown matters. A contractor who says "just trust me, I will send receipts" is not giving you a cost-plus contract. They are giving you a blank check.
If your project is large enough to justify it (typically $500K+), consider hiring an owner's representative or project manager to audit invoices on a cost-plus job. For a $700,000 addition, a project manager at $8,000-$15,000 who audits every receipt can easily save you $30,000-$50,000 in billing errors or questionable charges.
Platforms like Opsite give contractors a system to document every purchase order, receipt, and sub payment with digital records - if your GC is using a professional platform, ask them to share the job-level cost reports with you as part of your cost-plus transparency agreement. That kind of real-time visibility protects both of you.
For a full breakdown of what kitchen remodels actually cost in 2026, see our kitchen remodel cost guide. If you want to understand the full scope of how professional contractors manage projects, Opsite's features page shows the operational systems behind well-run jobs.
Frequently Asked Questions
Which contract type is better for a kitchen remodel?
Fixed-price is better for a kitchen remodel if you have complete drawings and a finalized material selection. It gives you budget certainty and protects you from cost overruns. If your design is still evolving or the kitchen has unknown conditions (old plumbing, asbestos, structural surprises), cost-plus with a Guaranteed Maximum Price is the safer structure.
Can a contractor change the price on a fixed-price contract?
Only through a signed change order. If your scope stays exactly as written, the price holds. The most common way fixed-price contracts escalate is through scope creep - small additions that each get their own change order. Get a clear change order procedure in writing before you sign: all changes in writing, with pricing and your signature, before any work begins.
What is a Guaranteed Maximum Price (GMP) and do I need one?
A GMP is a cap on your total exposure in a cost-plus contract. The contractor passes through actual costs plus markup, but once the total reaches the agreed maximum, they absorb anything beyond it. If you are signing a cost-plus contract, negotiate a GMP. Without one, your final cost is genuinely unknown.
How much contingency should I add to my remodel budget?
Add 15-20% on top of your signed contract value. For a fixed-price contract, that contingency covers change orders and items you decide to add. For cost-plus, it covers overruns beyond the estimate. Ten percent is not enough. Projects regularly hit unexpected conditions - especially in homes older than 20-25 years.
What is a draw schedule and why does it matter?
A draw schedule defines when you pay your contractor and ties each payment to completed, inspected work. It prevents you from pre-funding work that has not happened. Standard structure: a deposit at signing (California law caps it at 10% or $1,000, whichever is less for licensed contractors), then milestone payments as work is completed and inspected.
Do I need a lien waiver even if I paid the contractor?
Yes. Paying the GC does not protect you if the GC has not paid their subcontractors or suppliers. A mechanic's lien can be filed against your property by any unpaid party in the chain, even if you paid the GC in full. Get a conditional lien waiver from the GC and major subs at every payment. Get unconditional lien waivers at final payment.
How do I verify a contractor's license in California?
Go to cslb.ca.gov and use the license lookup tool. Check that the license is active, the bond is current, and there are no disciplinary actions or pending complaints. This takes 30 seconds and should be the first thing you do before any serious conversation with a contractor.
What is a typical GC markup on materials and labor in 2026?
In California, legitimate GC markup on cost-plus projects runs 15-25% of total project costs, based on 2026 construction cost data. This covers overhead, insurance, licensing, and profit. Be cautious of markups below 10% - either costs are being hidden elsewhere or the contractor is not properly insured and bonded.