Subcontractor Agreements in Ontario

A subcontract sits one level down from the head contract between an owner and a general contractor, but it is its own, legally distinct agreement. A subcontractor’s rights and obligations come primarily from the terms it actually signs with the general contractor, not from the head contract it may never see in full. That said, many subcontracts incorporate certain head contract terms by reference, which is one reason it is worth asking to see the relevant portions before signing rather than assuming the two agreements line up neatly.

This layered structure is part of why Ontario’s construction contract framework and its lien and payment protections exist: they are designed to flow down through the contracting chain, from owner to general contractor to subcontractor and, often, to sub-subcontractors and suppliers below that.

Because a subcontractor is typically not a party to the head contract, it can be at a practical disadvantage when it comes to knowing what the owner and general contractor actually agreed to — including the project schedule, payment certification process, and any specific standards the owner demands. Asking for the relevant excerpts of the head contract, rather than assuming the subcontract tells the whole story, is a reasonable and common request before signing on to a project of any size.

A well-drafted subcontract covers the same fundamentals as any construction contract, but from a narrower, trade-specific angle. The scope of work should describe exactly what the subcontractor is responsible for, including materials supplied, standards to be met, and coordination points with other trades on site. The price should be clear about whether it is fixed, unit-priced, or subject to adjustment, and the schedule should set out start dates, milestones, and how delays caused by other trades or site conditions are handled.

Change orders deserve particular attention in a subcontract, since trade work is especially prone to scope creep on site — an extra outlet here, a revised fixture location there — that can add up significantly if not documented. A requirement that any change be confirmed in writing before the extra work proceeds protects both sides. See our guide to change orders in Ontario construction for more detail.

Two clauses that sound similar can have very different effects. A pay-when-paid clause ties the timing of payment to the subcontractor to when the general contractor receives payment from the owner, but it generally does not eliminate the underlying obligation to pay — it mainly delays it. A pay-if-paid clause goes further, attempting to make payment conditional on the general contractor actually being paid at all, effectively shifting the risk of owner non-payment onto the subcontractor.

In practice, this means a subcontractor facing a slow-paying general contractor has more tools than the subcontract’s own wording might suggest, including the right to issue a proper invoice that starts statutory payment timelines running, and the right to refer a payment dispute to adjudication rather than waiting for litigation.

It is still worth reading a subcontract’s payment clause closely, since the practical effect of pay-when-paid language can still matter for cash flow timing even where it cannot be used to avoid payment indefinitely. A subcontractor negotiating a new agreement may reasonably ask for a backstop date — a fixed number of days after invoicing by which payment is due regardless of the general contractor’s own payment status — to avoid open-ended delay even where the underlying obligation to pay is not in doubt. Our overview of prompt payment in Ontario covers the relevant deadlines in more depth.

Most subcontracts require the subcontractor to carry commercial general liability insurance at a specified minimum, often naming the owner and general contractor as additional insureds, along with proof of current WSIB coverage before work can begin on site. It is worth checking these requirements against what the subcontractor’s actual policy provides rather than assuming the two automatically match, since a mismatch can surface at the worst possible time — after an incident, rather than before one.

Indemnity clauses require closer reading than they usually get. A broadly worded indemnity can require a subcontractor to cover losses connected to the project even where its own work was not at fault, particularly on a site with several trades working in close proximity. Understanding exactly what liabilities an indemnity clause assigns — and whether the subcontractor’s insurance would actually respond to that liability — is worth doing before signing, not after a claim arises.

It is also worth checking whether an indemnity is mutual or runs only one way, and whether it is limited to losses caused by the subcontractor’s own negligence or drafted broadly enough to capture losses merely connected to its presence on site. A subcontractor that signs an unusually broad indemnity without reviewing it against its own coverage may discover, only after an incident, a meaningful gap between what it agreed to cover and what its policy will actually pay.

One of the more important protections for subcontractors is that lien rights under the Construction Act arise from the statute itself, not from what the subcontract or head contract says. A clause attempting to waive a subcontractor’s lien rights in advance is generally not enforceable, which means a subcontractor retains the ability to register a lien against the property even where the governing contracts are silent — or try to say otherwise.

This protection exists because the Construction Act is designed to secure payment across the entire contracting pyramid, not just between the two parties who happen to sign a particular agreement. A subcontractor several layers removed from the owner can still generally look to the lien remedy against the property itself, which is part of why lien rights are treated as a statutory floor rather than something negotiated away in a private contract.

These rights come with firm deadlines. A lien generally must be preserved within 60 days of the relevant triggering event — such as substantial performance of the head contract, completion of the subcontract, abandonment of the project, or the subcontractor’s own last supply of services or materials — and then perfected within a further 90 days. Holdback, generally 10 percent of the contract price, is held specifically to protect these lien rights and give subcontractors and suppliers a pool of funds to draw against. Our guides to construction liens and holdback requirements cover both in more detail.

Before signing a subcontract, it is generally worth reading the full document, not just the pricing page, and asking to see any relevant head contract terms that are incorporated by reference. Tracking invoice dates and payment deadlines closely matters once work is underway, since statutory timelines for both prompt payment and lien preservation run on fixed clocks that do not pause for an ongoing conversation about payment.

Where a payment dispute does arise, adjudication under the Construction Act and, where needed, a construction lien are both tools available to a subcontractor independently of what the subcontract’s payment clause says. Our guide to discharging a construction lien and our adjudication overview walk through how each process generally works. This article is general information about how subcontractor agreements commonly operate in Ontario, not legal advice for a specific dispute — our contact page can help point toward further resources.