You did the work, the money stopped, and you have no contract with the owner. That gap is what makes a subcontractor dispute in Ontario harder than it looks, since the party holding the funds is not the party you can sue on the contract. The Construction Act closes the gap with information rights, notices and deadlines. The January 1, 2026, amendments left the lien periods alone but reshaped invoicing, termination notices and adjudication.

You Have No Contract With the Owner, but You Do Have Section 39

Start by finding out what is actually happening above you. Section 39 of the Construction Act lets a lien claimant or trust beneficiary demand written information from people it never contracted with.

Ask the owner and you can require the contract price, the state of accounts between owner and contractor, and a copy of any labour and material payment bond. Ask the contractor and the list differs. You can require the state of accounts between you and it, whether your subcontract is subject to certification, whether it has already been certified complete, and any bond posted under the subcontract.

Either way the state of accounts must itemise what was supplied, what was paid, the holdbacks, anything retained by way of set-off, and the balance owing.

The recipient has a reasonable time, and no more than twenty-one days, to answer. Refusing carries consequences. A court may order the information produced with costs, and someone who fails to provide it, or who knowingly or negligently misstates it, is liable for the resulting damages.

Send that request early. An Ontario subcontractor dispute is usually an argument about numbers nobody has shown you, and section 39 is how you finally see them.

The Notice That Lets a Contractor Withhold Your Money

Contractors say the owner has not paid them. Sometimes that is true, although it answers only half of an Ontario subcontractor dispute.

Section 6.5 requires a contractor who gets paid to pay its subcontractors within seven days, rateably where the payment came in part. Where the owner pays nothing, the contractor must still pay you no later than thirty-five days after it gave the owner its proper invoice. Where the owner served a notice of non-payment, the contractor may pass that upstream problem down to you only by meeting several strict conditions.

It must give you a notice of non-payment in the prescribed form, within seven days of receiving the owner’s notice. That notice must state the amount being withheld, attach a copy of that notice, and include an undertaking to refer the matter to adjudication with the owner no later than twenty-one days after giving you the notice. Miss any element and the shield is gone. That single failure ends many a subcontractor dispute in Ontario without a hearing.

That undertaking is the part contractors forget. A contractor who blames the owner but gives no undertaking to adjudicate has not complied with that route, so the money is payable whether or not the owner ever paid. The contractor may still dispute your invoice on its own grounds, although only by giving its own notice of non-payment no later than thirty-five days after it gave the owner its proper invoice.

Pay-when-paid is rarely the real argument

Subcontractors assume the clause in their subcontract settles everything, and it seldom does.

Ontario courts have not yet squarely decided how a pay-when-paid clause interacts with the prompt payment regime. Meanwhile section 4 voids any agreement that the Act does not apply, and section 5 deems every contract and subcontract amended to conform to the Act. The statutory timetable and the notice requirements run regardless. What remains unsettled is whether such a clause can still defeat the underlying contractual entitlement.

Therefore, you should not build a subcontractor dispute in Ontario around the clause. Ask instead whether the contractor actually served the right notice, in the prescribed form, on time, with the undertaking attached.

Where an Ontario Subcontractor Dispute Is Usually Lost: Your Lien Clock

The mistake here is a natural one. Subcontractors watch the project schedule when they should be watching their own file.

Under section 31, a subcontractor’s right to register a lien expires sixty days after the earliest of several triggers. Those triggers include publication of the certificate of substantial performance for the prime contract, your own last supply of services or materials, certification that your subcontract is complete, and completion, abandonment or termination of the contract. Termination now has its own wrinkle, since a notice of termination must be published within seven days and that publication date counts as the termination date. Where several notices appear, the first one controls.

Certification is the trigger that catches people. Under section 33 a payment certifier may certify a subcontract complete at the contractor’s request, and that certification date then counts as your last supply, so your clock can close while the project carries on for another year.

Returning to fix your own deficiencies generally does not restart anything either. A repair visit feels like supply, yet it rarely extends the last supply date.

One improvement, one clock

Working under more than one subcontract does not multiply your clocks, though. In Prasher Steel Ltd. v. Pre-Eng Contracting Ltd., 2024 ONSC 4772, a steel subcontractor working under two separate subcontracts on the same school project registered a single lien. The contractor argued each subcontract needed its own, and the trial judge agreed. The Divisional Court reversed on that point, holding that the clock runs from the date the subcontractor last supplied to the improvement, however many subcontracts it worked under.

Neither subcontract had been certified complete, so the Court did not need to address section 33. On the wording of the Act, certification should still operate subcontract by subcontract, which means the two rules likely sit side by side.  Transition provisions also put that case under the former Construction Lien Act and its forty-five-day period, so follow the reasoning rather than the number.

Adjudication Reaches You After You Have Left the Site

Adjudication is interim binding decision-making built into the Act, and it now reaches a subcontractor dispute in Ontario later than it used to.

Since January 1, 2026, a party may give notice of adjudication up to ninety days after a contract ends, whether by completion, abandonment or termination. For a subcontract the ninety days runs from the earliest of that date, the certification of your subcontract, and your own last supply. The transition rules matter here, since the new window may not reach contracts signed before that date. Confirm which regime governs yours before relying on it.

That window matters mainly to subcontractors, who often discover an Ontario subcontractor dispute only after demobilising. Previously the door shut on completion.

Two further points are worth knowing. The adjudicable subject matter now sits in a regulation rather than the Act, and it reaches scope of work, requests for a change in the contract price and extensions of time where resolving them is reasonably necessary to decide another listed matter. Section 13.8 also lets any party seek consolidation of adjudications on the same improvement. Absent consent the adjudicators must agree, so another party may pull you into one you did not start.

Speed does not mean anything goes. In Ledore Investments Ltd. v. Dixin Construction Ltd., 2024 ONSC 598, a steel subcontractor went unpaid on roughly $349,000 of invoices, even though the owner had paid the contractor and no timely notice of non-payment arrived for those invoices. The adjudicator nonetheless refused payment on a point neither side had argued, and the Divisional Court set that determination aside and sent it back, holding that the right to be heard applies even to fast interim adjudication.

What to Do Next: When to Call a Lawyer

Move on paper before you move on the merits. A subcontractor dispute in Ontario turns on notices and dates far more often than on workmanship.

Calendar your own lien deadline from every possible trigger, not from the project’s. A certificate of completion of your subcontract must reach you within seven days, although you should ask the contractor in writing rather than wait for it.

Serve a section 39 request as soon as payment slips. It is cheap, it starts a twenty-one day clock, and the answer tells you whether the money exists and whether a payment bond stands behind it.

Check any notice of non-payment against the four requirements above, particularly the undertaking to adjudicate. Keep delivery slips, daily reports and site photographs too, because the last day on site is the most litigated fact in lien practice.

Finally, treat the remedies as stacking rather than competing. Adjudication moves cash fastest, a lien creates leverage, and a trust claim can reach directors and officers personally, although it is a separate action with its own proof and its own limitation period.

The Act rewards whoever protected their dates. If you are facing a subcontractor dispute in Ontario, or a notice of non-payment just landed, contact Cowan before the deadline decides it for you.