When Should a Contractor File a Lien? 4 Triggers

The honest answer is that filing a lien is a calendar decision before it is a collections decision. Your right to lien expires on a date the statute picks, usually 30 to 60 days after completion or last supply in Canada and 90 to 180 days in most US states, and that date has nothing to do with how patient you have been. Most contractors who lose lien rights lose them by being reasonable for too long.

The four triggers that start your clock

There are only four events that typically start a lien period, and none of them is "the invoice went past due."

1. Last supply of services or materials. The most common trigger, and the one most online guides quote. Your last real day of work on the improvement, not the last day you sent an email about it.
2. Publication of a certificate or declaration of substantial performance. In Ontario this governs a general contractor's clock instead of last supply. Under section 31 of the Construction Act, a contractor's period runs from publication of the certificate, or from completion, abandonment or termination of the contract. As the construction-lien practice at Elias Defence puts it, a contractor's clock is never triggered by last supply at all, so it can have started months before they left site.
3. Deemed completion. Ontario deems a contract completed once the cost to finish it or correct known defects drops below the lesser of 1% of the contract price or $5,000. Lerners LLP flags the consequence plainly: the preservation period may already be running while you are still on site doing punch list work. On a $200,000 contract, once you are down to under $2,000 of remaining work, the clock has likely started.
4. Abandonment or termination. Ontario now requires a notice of termination to be published within seven days of termination, and where more than one is published, the first one starts expiry running.

That third trigger is the trap. The mental model most owners carry is "I finish, I invoice, I wait 30 days, I chase for a month, then I think about a lien." On a deemed-completion basis in Ontario, that sequence can put you past 60 days before you have made a single decision.

Deadline by province, and why the US comparison misleads

Canadian lien windows are materially shorter than American ones, which matters because most of the content that ranks for lien questions is written for US states.

Deadlines compiled from the NCS Credit Canadian mechanic's lien guide and provincial statute summaries. Confirm your own date against the current statute or with a lawyer before relying on it.

For contrast, US states typically run 90 days from last furnishing in California, Florida and Georgia, 180 days in North Carolina, six months in Pennsylvania, and up to eight months on residential work in New York. Most US states also require a preliminary notice, often within 20 days of starting work, that Canadian provinces do not. Quebec is the exception north of the border: a declaration of contract must be served on the owner before you furnish, and the hypothec is limited to what you supplied after that notice.

So the American advice to "send your 20-day notice and you have 90 days" is not just unhelpful in Canada, it is dangerously slack by about a month.

What a lien actually does, and when it does nothing

A lien does not make anyone pay you. It makes you a problem on someone's title.

An owner with a registered lien generally cannot close a sale, complete a refinancing, or draw the next advance under construction financing until it is dealt with, and lenders will not fund over it. That is the entire mechanism. It creates a commercial reason to settle that is independent of who is right on the merits, which is why lien claims settle at rates that ordinary debt claims never reach.

The corollary matters just as much. If the owner has no mortgage activity, no sale planned, and no construction lender, a lien is a slow instrument. A contractor on r/Contractor filed one in California and reported that the customer "didn't give a F about me filing it." That is a rational response from someone who is not transacting.

Before you file, ask what the owner is about to do with the property. A homeowner mid-renovation on a HELOC draw is highly exposed. A landlord who has owned the building outright for twenty years is not.

The three outcomes, with real numbers

Search results for lien questions are written almost entirely by law firms explaining the statute and by filing services selling the filing. Neither publishes the distribution of outcomes. Contractors do, in public.

Outcome one: it works, fast and cheap. A contractor who was ghosted on a final payment gave 72 hours' written notice, then had a service file the lien. "Today I got PAID! It cost me just under $500 it was worth it for the amount of the project. From start to finish was about a week." Another in Massachusetts filled out a form at the courthouse on a $12,000 debt: $200 to file, $200 to remove, paid soon after.

Outcome two: it stalls. You registered on time, the owner shrugged, and now you are staring at the enforcement deadline. A California contractor owed $14,800 described the bind exactly: the lien was served and recorded properly, but because the business is incorporated, he cannot represent it himself in a foreclosure action, and lawyers quoted $200 to $400 an hour. The recorded lien is real. The ability to enforce it is a separate purchase.

Outcome three: it consumes you. The most upvoted thread in this space on r/Contractor is titled "Not rich enough to get paid." The owner filed a lien against a wealthy customer, litigated for two years, ran up $70,000 in legal fees, and at the courthouse door was told: "you don't have the money to continue litigating this, so it's best you agree to a mutual walkaway now." His conclusion was that the legal system protects the party who can afford it.

Same instrument, three completely different businesses at the end. What separates them is not luck. It is the size of the debt relative to enforcement cost, whether the owner is transacting, and whether the paperwork was good enough that nobody wanted to test it.

A break-even framework, by amount owed

Use the debt size to pick the route before you pick the paperwork.

The number that decides this is not what you are owed. It is what you are owed minus what it costs to collect, and the second half of that subtraction is the half most contractors never price out before filing.

The route almost nobody uses

Here is the part missing from essentially every article ranking for this query in Canada.

If your project is in Ontario, you do not have to choose between a lien foreclosure and small claims court. The Construction Act gives you statutory adjudication, administered by the Ontario Dispute Adjudication for Construction Contracts. The adjudicator must issue a determination within 30 days of receiving the claimant's documents, and a certified determination can be filed with the court and enforced as if it were a court order.

The published fee schedule, approved October 1, 2025, is the reason this matters to a small operator. Where the parties and adjudicator cannot agree a fee, ODACC sets it:

The referral fee to start is $0 below $50,000, and the certification fee is $0 below $50,000. The adjudication fee is split equally between the parties unless the adjudicator orders otherwise.

Run that against the California contractor owed $14,800. On an Ontario project, the equivalent claim sits in the $1,700 tier, split, so roughly $850 plus HST, with a binding written determination inside 30 days. Against $200 to $400 an hour for a foreclosure action, that is not a close call.

Two caveats, because this is not free money. Until recently you had to start adjudication before the contract was complete, which ruled it out for exactly the disputes that arise at final payment. That changed on January 1, 2026: under the Bill 216 and Bill 60 amendments now in force, parties have a 90-day window after completion, abandonment or termination to give notice of adjudication. And the economics are provincial, not national. Alberta's authority, ARCANA, states on its own site that appointment and adjudicator fees "begin at almost $3000," are often initially borne by the applicant, and that it does not provide enforcement services. It also notes, usefully, that registering a lien does not preclude or interrupt an adjudication.

That last point is the practical takeaway. In Alberta and Ontario alike, preserving the lien and adjudicating are not alternatives. Preserve the lien because the deadline is unforgiving, then adjudicate because it is the cheap way to get a decision.

What kills a lien before you ever file it

Four failure modes, all of them decided long before the dispute.

You are not licensed. In many jurisdictions an unlicensed contractor has no enforceable contract and no lien rights. Practitioners in the r/Contractor thread about an unlicensed HVAC sub were blunt: the board complaint may be noise, but the licensing gap is not.

You missed the preliminary notice. Quebec requires a declaration of contract served on the owner before you furnish. Most US states require a notice within about 20 days of starting. Miss it and the lien is void no matter how good the debt is.

You registered against title on a public job. On Crown, municipal or railway property in Ontario the lien does not attach to the land at all. You preserve by giving written notice of lien to the owner, to the prescribed office on Crown premises or to the clerk on municipal premises, within the same 60 days. A subcontractor who registers on title and discovers the error on day 65 has no lien and no way back.

You signed an unconditional release to unblock a draw. The consensus among working contractors is unanimous and worth quoting: "payment first. always." Use a conditional waiver that takes effect only when the payment clears. One contractor's rule: the only time to sign a release before funds clear is when the cheque is written directly from a lender's escrow account. Another builder confirmed his own releases all state the lien is released upon successful payment, and that no vendor from a local supplier to a national one has ever objected. It is normal practice, not an insult.

The paperwork that decides whether a lien collects

Notice what the contractor who got paid in a week actually had, because it is a checklist rather than a personality:

• A signed copy of the estimate with a deposit, on a system that timestamps the signature.
• Photos and video of the job from start to finish.
• An online invoice that could be resent daily with a payment link.
• A dated written notice giving 72 hours before filing.

None of that is legal work. It is job records, produced during the job, by a business that keeps them by default. When a lien gets contested, the defence is nearly always the same one the "Not rich enough to get paid" contractor faced: poor workmanship, raised for the first time when the bill came due. Contemporaneous photos and a signed scope are what turn that from an argument into a document review.

This is the same discipline that prevents the dispute in the first place. Our guide to what to do when a customer will not pay covers the escalation sequence, and collecting a deposit before starting work covers the structural fix. If job records currently live across a phone gallery, a truck glovebox and memory, a custom CRM is the difference between a lien you can support and one you quietly drop.

The sequence to run

1. Day you finish: calculate and record your lien expiry date. Do this before invoicing.
2. Invoice same day, with terms in writing and a payment link.
3. Day 7 past due: written reminder. Nothing dramatic.
4. Day 14: phone call, then confirm the conversation by email so it exists in writing.
5. Day 21: notice of intent to lien, with a hard date about seven days out. Several contractors report this alone resolves most cases, and one has his materials supplier send it so he is not the one playing the heavy.
6. Well before expiry: register the lien. Do not aim for the last day. Ontario moves a deadline falling on a weekend or registry closure to the next open day, which is a reason to know your date precisely, not a reason to cut it fine.
7. Immediately after: decide the enforcement route on the break-even table above, and diarize the enforcement deadline the same day.
8. On payment: discharge promptly. Leaving a satisfied lien on title exposes you to a slander of title claim in some jurisdictions.

The bottom line

File a lien when the debt is real, the deadline is live, and the owner has something to lose from a cloud on title. Skip it when the amount is smaller than the cost of enforcing it and the owner is not transacting, and put your energy into a notice of intent and a small claim instead.

But the decision that actually determines the outcome happens earlier than any of that. It happens when you write the expiry date in the job file on your last day on site, when you get a signed scope with a timestamp, and when you invoice the same day rather than the following week. Contractors who do those three things rarely need a lien. The ones who do need it still have the right to use it.

This is general information for business owners, not legal advice. Lien statutes are jurisdiction specific and the deadlines are unforgiving, so confirm your own dates with a construction lawyer or paralegal before acting.