How to File a Construction Lien in Ontario (Step-by-Step 2026 Guide)

How to File a Construction Lien in Ontario

The Ontario Construction Act (formerly the Construction Lien Act) protects contractors, subcontractors, and suppliers who aren't paid for work or materials. Filing a construction lien is a powerful legal tool — but the deadlines are strict. Miss them, and you lose your rights entirely.

Who Can File a Lien?

Under the Ontario Construction Act, anyone who supplies services or materials to an "improvement" can file a lien:

Critical Deadlines

The 60-Day Rule: You must preserve your lien within 60 days of the last day you supplied services or materials to the project. This is non-negotiable.

The 90-Day Rule: After preserving the lien, you have 90 days to perfect it by starting a court action.

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Step-by-Step Filing Process

Step 1: Calculate Your Deadline

Count 60 days from the last day you performed work or supplied materials. If the project has been certified as "substantially complete," the 60-day clock starts from that certification date.

Step 2: Prepare the Claim for Lien

Your lien document must include:

Step 3: Register the Lien

File the Claim for Lien at the Land Registry Office (now ServiceOntario) where the property is located. The registration fee is approximately $70-$100.

Step 4: Serve the Lien

Serve a copy of the registered lien on the property owner within 30 days of registration.

Step 5: Perfect the Lien

Within 90 days of preservation, you must commence a court action. File a Statement of Claim in the Superior Court of Justice.

The 10% Holdback Rule

Ontario law requires every person who pays for construction work to hold back 10% of the price of the work/materials for 60 days. This holdback creates a trust fund that protects subcontractors and suppliers.

Costs Involved

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Common Mistakes

Alternatives to Filing a Lien

Before filing a lien, consider:

Use our free Lien Generator tool to create Ontario-compliant lien documents instantly.

• General contractors
• Subcontractors (all tiers)
• Material suppliers
• Equipment rental companies
• Architects and engineers (for services related to construction)

• Your name and address
• The owner's name and address
• A description of the property (legal description)
• The amount claimed
• A description of the services/materials provided
• The date of last supply

• The holdback applies to every level of the payment chain
• If an owner pays the full amount without holding back 10%, they may be liable to lien claimants
• The holdback can be released 60 days after the contract is substantially completed (if no liens are preserved)

1. Miscalculating the 60-day deadline — Count carefully from the LAST day of work
2. Wrong property description — Must match the legal description exactly
3. Liening the wrong property — Condos and subdivisions have specific rules
4. Not perfecting within 90 days — The lien expires automatically
5. Not serving the owner — Service is required within 30 days of registration

• Sending a demand letter (use our free template)
• Negotiating a payment plan
• Filing a complaint with the Ontario College of Trades
• Using our Should I Sue? Assessment tool