- Before sending anything, match your invoice against the written contract and any change orders.
- Under the Construction Act, an unpaid contractor or supplier can register a lien against the property — but only within a short preservation period (60 days, as of mid-2026 — verify the…
- A demand letter — ideally from a lawyer — puts the homeowner on formal notice and typically sets out: - The exact amount owed and how it's calculated - The contractual basis for the debt…
Finishing a job only to have the homeowner delay, dispute, or flatly refuse to pay the final invoice is one of the most frustrating positions a contractor can be in. Unlike an ordinary consumer debt, unpaid construction work comes with its own specialized legal tool — the construction lien — and that tool runs on strict, unforgiving deadlines that most other debt collection situations don't have. Knowing the right order of steps, and moving quickly, matters more here than in almost any other kind of collection.
This guide walks through what an Ontario contractor whose client won't pay can do, from the first written notice through to enforcement.
Step 1 — Confirm the Amount Owed and Review the Contract
Before sending anything, match your invoice against the written contract and any change orders. Confirm you followed the agreed payment schedule and milestones, and that the amount you're claiming is exactly what the contract and any approved changes actually support. A demand or lien based on an inflated or unclear figure is easier for the other side to challenge.
Step 2 — Move Quickly, Because Lien Deadlines Are Short
This is the single most important difference between construction debt collection and an ordinary unpaid invoice. Under the Construction Act, an unpaid contractor or supplier can register a lien against the property — but only within a short preservation period (60 days, as of mid-2026 — verify the current period), followed by a further short window to perfect the lien (90 days from the last day it could have been preserved, as of mid-2026 — verify). These deadlines run from specific statutory trigger dates and keep running regardless of ongoing settlement talks. Missing them generally ends your lien remedy — although your underlying claim for the debt itself may still be pursued separately through an ordinary court action, subject to Ontario's general limitation period.
If a lien is even a possibility for your project, talk to a lawyer immediately rather than waiting to see if informal collection efforts work first.
Step 3 — Send a Formal Demand Letter
A demand letter — ideally from a lawyer — puts the homeowner on formal notice and typically sets out:
- The exact amount owed and how it's calculated
- The contractual basis for the debt
- A firm deadline to pay
- The consequence of continued non-payment: a lien, a court claim, or both
Step 4 — Decide: Lien, Court Claim, or Both
A construction lien secures your claim against the property — it doesn't, by itself, put money in your account. You generally still need to pursue and prove the underlying debt (often through the lien action itself, or a separate claim) to actually collect. Many contractors pursue both together: the lien preserves your position against the property while the underlying claim moves through the courts.
| Track | Best For | Notes |
|---|---|---|
| Small Claims Court | Claims up to $50,000, exclusive of costs and interest (as of mid-2026 — verify) | Designed for self-represented parties; licensed paralegals may also represent you |
| Simplified Procedure | Claims up to $200,000 (as of mid-2026 — verify) | A streamlined version of the ordinary Superior Court process |
| Ordinary Superior Court procedure | Larger or more complex claims above that ceiling | Full discovery and trial process; a lawyer is strongly recommended |
A defendant served in Ontario generally has a set number of days to respond once a claim is properly served (longer if they're served elsewhere in Canada, the U.S., or further afield). If they don't respond in time, you can generally move for default judgment without a full trial.
Step 5 — Understand How the Statutory Holdback Fits In
If you're a subcontractor or trade being paid through a general contractor, or if the owner is holding back the statutory percentage required under the Construction Act (10% of the price of your services or materials, as of mid-2026 — verify), remember that holdback exists mainly to protect the lien rights of everyone in the payment chain — it's a separate mechanism from any dispute over the specific amount you're owed. Its release is generally tied to the expiry of the applicable lien period.
Step 6 — If You Get a Judgment, You Still Have to Enforce It
A judgment is not the finish line. Ontario law provides tools to enforce it, including garnishment (of a bank account or wages), a writ of seizure and sale against property or other assets (generally valid for six years from issue and renewable, as of mid-2026 — verify), and an examination of the debtor about their income and assets. The court doesn't collect on your behalf — enforcement takes active steps on your part.
Frequently asked questions
Can I still register a lien if I've already been paid part of what's owed?
Generally yes, for the unpaid balance, and the same short deadlines apply from the applicable statutory trigger date. A lawyer can help confirm the correct date for your specific project, since getting it wrong can cost you the remedy entirely.
What happens if I miss the lien deadline?
Your lien remedy is generally lost, but you may still be able to sue on the underlying debt through an ordinary court claim, subject to Ontario's general limitation period. Missing the lien deadline is still a real loss, though — a lien gives you leverage against the property that an ordinary debt claim doesn't.
Do I need a lawyer to register a construction lien?
It's not a strict legal requirement, but the deadlines and procedural requirements are technical and unforgiving. Given how much can be lost by missing a step, many contractors get legal help for this specific process even if they handle other business matters themselves.
What if the homeowner disputes the quality of my work as a reason not to pay?
That turns the dispute into a deficiency claim, which the homeowner would need to prove. It doesn't automatically stop you from pursuing your invoice or preserving a lien, but you should expect the amount to be contested and plan your evidence accordingly.
Is Small Claims Court realistic for an unpaid invoice on a smaller job?
Often, yes — the current monetary jurisdiction covers many contractor invoices, and it's generally faster and less expensive than the ordinary Superior Court process. Confirm the current threshold before deciding which court fits your claim.
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