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Substantial Completion in Ontario Home Construction
Ontario Construction Act • Homeowner guide
Substantial Completion in Ontario Home Construction
Ontario law calls it substantial performance. It is not the day the homeowner moves in, the permit closes or the builder says the house is 97% finished. Two separate tests must be met: the improvement must be ready for its intended use, and the cost to finish and correct known defects must fit the statutory 3%-2%-1% formula.
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The legal test has two parts
Both must be true. The home—or a substantial part of it—must be ready for the purpose intended, and the cost to complete the contract and correct known defects must not exceed the statutory threshold.
First $1,000,000 of contract price
3%Next $1,000,000
2%Everything above $2,000,000
1%$800,000 contract$24,0003% of the first $800,000
$1.5 million contract$40,000$30,000 + $10,000
$3 million contract$60,000$30,000 + $20,000 + $10,000
$5 million contract$80,000$30,000 + $20,000 + $30,000
This is a ceiling, not a target. A project does not become substantially performed merely because the contractor’s unpaid balance falls below the formula. The remaining completion and known-defect correction cost must be assessed honestly.
A worked custom-home example
A custom home contract began at $1,350,000. Approved changes increased the contract price to $1,500,000. The home is ready to live in, but exterior stairs, several doors, final grading and known interior deficiencies remain.
The contractor estimates the remaining work at $31,000. The owner’s consultant estimates $46,000. The statutory threshold is not determined by taking an average. The parties need a supportable cost to complete and correct the known defects.
Threshold calculation
3% × first $1,000,000 = $30,000
2% × next $500,000 = $10,000
Maximum remaining cost: $40,000
If the defensible remaining cost is $46,000, the numerical test is not yet met. If enough work is completed to reduce that cost to $39,000—and the home is ready for intended use—the contract may meet the statutory test.
What happens from inspection to final completion
1. Before certification
Reconcile the contract price, approved changes, incomplete work and all known defects. Confirm the improvement is ready for intended use. Do not use the contractor’s final invoice as the cost-to-complete calculation.
2. Form 9 is prepared
The payment certifier determines substantial performance on the contractor’s application. If there is no payment certifier, the owner and contractor determine it jointly and both sign the prescribed certificate.
3. The certificate is published
The contractor publishes Form 9 on a construction trade news website. A certificate or court declaration has no effect for this Part until publication. The publication date can trigger lien-preservation consequences.
4. Finishing work continues
Work supplied after the certified substantial-performance date is subject to a separate 10% finishing holdback. The remaining work should have its own priced list, schedule and correction responsibility.
5. Final completion and closeout
Finish the remaining work, correct deficiencies, reconcile changes, deliver manuals and warranties, complete inspections and address finishing-holdback and lien requirements. Substantial performance was not the end of the contract.
What can still be unfinished?
Potentially compatible with substantial performance
- Minor interior touch-ups
- Limited seasonal landscaping
- Small quantities of trim or hardware
- Final documentation and manuals
- Known deficiencies whose real correction cost fits the formula
Do not assume these are acceptable
- Unsafe stairs, guards or exits
- Water entry or exposed building envelope
- Systems not operating for intended use
- Large unfinished rooms or exterior work
- Known defects whose correction cost exceeds the formula
The Act does not contain a universal list of acceptable unfinished items. Readiness for intended use, safety, approvals, contract obligations and actual completion cost all matter.
Six things substantial performance does not mean
Not enoughThe homeowner moved inOccupancy or use can satisfy part of the test, but the cost-to-complete test must also be met.
Not enoughThe permit is closedMunicipal approval does not itself certify substantial performance under the Construction Act.
Not enoughOnly cosmetic work remainsThe actual cost to complete and correct known defects still has to fit the statutory formula.
Not enoughThe certificate was signedA certificate or court declaration has no statutory effect for this Part until it is published.
Not enoughAll holdback is releasedSince 2026, basic holdback follows the mandatory annual-release regime; finishing work has separate holdback.
Not enoughThe project is finally completeSubstantial performance can occur while meaningful finishing work and deficiencies remain.
Publication, liens and holdback after January 1, 2026
What publication does
- Gives statutory effect to the Form 9 certificate
- Can trigger the 60-day lien-preservation period for contractors and relevant subcontractors
- Creates the dividing date for basic work and later finishing work
- Makes the certified substantial-performance date legally important
What changed in 2026
- Basic holdback is now released through mandatory annual payments after each contract anniversary
- Substantial performance does not automatically release all accrued basic holdback
- Separate 10% finishing holdback still applies to later work
- Transition rules may affect older contracts and require legal review
Do not calculate lien or holdback dates yourself from the certificate date alone. Publication, claimant category, annual release, transition rules, completion, abandonment and termination can change the analysis.
Homeowner action plan before Form 9 is signed
Reconcile the contract priceUse the signed price plus approved changes and any applicable adjudication adjustments.
List all remaining workInclude incomplete work and the real cost of correcting every known defect.
Confirm intended useDetermine whether the improvement or a substantial part is actually ready for its intended purpose.
Check the 3%-2%-1% ceilingDo not certify from a rough percentage or the contractor’s unpaid balance.
Confirm the certifierUse the payment certifier, or joint owner-contractor determination when none exists.
Review Form 9 carefullyNames, service addresses, property description, PINs and substantial-performance date must be accurate.
Plan publicationThe contractor publishes on a construction trade news website; if it does not, another person may publish.
Protect lien and holdback timingHave an Ontario construction lawyer calculate current preservation and release consequences.
Separate finishing workCreate a priced completion list and retain 10% finishing holdback as later work is supplied.
Do not sign a broad releaseCertification should not accidentally waive deficiencies, warranty rights or unresolved changes.
Substantial completion FAQ
Is “substantial completion” the legal Ontario term?
The Construction Act uses “substantial performance of a contract.” People commonly say substantial completion, but contracts should distinguish the statutory test from their own completion milestones.
Can a house be substantially performed with unfinished work?
Yes. The improvement or a substantial part must be ready for intended use, and the cost to finish and correct known defects must fall within the statutory 3%-2%-1% threshold.
Who signs the certificate?
On the contractor’s application, the payment certifier determines and signs Form 9. If there is no payment certifier, the owner and contractor make the determination jointly and both sign.
Does signing Form 9 start lien deadlines?
The certificate has no effect for Part V until it is published. Publication can trigger lien-preservation timing, but the exact deadline depends on the claimant and project events.
Does substantial performance release the 10% basic holdback?
Not automatically under Ontario’s current 2026 regime. Basic holdback is now subject to mandatory annual release. Substantial performance remains important for lien timing and creates separate finishing holdback on later work.
What is finishing holdback?
After substantial performance, each payer retains 10% of the price of remaining services or materials as they are actually supplied until liens against that finishing holdback expire or are otherwise dealt with.
Related Ontario contract guides
Official references: Ontario Construction Act, O. Reg. 303/18 — Form 9, and O. Reg. 304/18 — publication rules.
Do not sign the certificate because the house “looks nearly done”
Upload the contract, change-order log, payment ledger, deficiency list, cost-to-complete calculation and proposed Form 9. Start with the Free Scan. The complete builder-reviewed Full Report is $99.99, and an independent Ontario construction lawyer can review certification and lien consequences from $499.99.
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ICFhome can establish realistic milestones, inspection procedures, finishing-work lists and payment controls before construction begins.
Reviewed July 30, 2026. General educational information only. This page is not legal advice, a substantial-performance certificate, a cost-to-complete opinion or a lien-deadline calculation.
