Subcontractor compliance: CRA verification, OH&S

Construction supply chains in Canada involve multiple tiers of subcontractors, each carrying distinct legal obligations around tax, occupational health and safety, competence, and worker welfare. For general contractors and project owners, verifying subcontractor compliance is not discretionary good practice. It is a legal requirement enforced through the CRA, provincial occupational health and safety regulators (such as Ontario's Ministry of Labour, Immigration, Training and Skills Development, and WorkSafeBC), and municipal building authorities, with penalties that range from financial assessments to criminal prosecution.

According to the Association of Workers' Compensation Boards of Canada (AWCBC), the construction sector consistently accounts for the highest number of workplace fatalities and a disproportionate share of lost-time injuries in Canada (AWCBC, National Work Injury Statistics). Rigorous subcontractor vetting is the primary mechanism to reduce these figures and ensure regulatory compliance across the supply chain.

The regulatory framework for construction subcontracting in Canada

Three legislative pillars govern how contractors and subcontractors interact in the Canadian construction industry.

Canada Revenue Agency (CRA) requirements

The CRA requires businesses to determine whether workers are employees or independent contractors and to meet corresponding tax obligations. For subcontractors, this involves verifying the subcontractor's Business Number, confirming GST/HST registration status, and ensuring proper invoicing. Contractors who fail to verify a subcontractor's status risk being assessed for unpaid source deductions (CPP, EI) plus penalties and interest if the CRA reclassifies the relationship as employment (CRA, Employee or Self-Employed). The Construction Industry Scheme requirements apply to all payments made to workers on construction sites. For work permit verification of temporary foreign workers, employers must use the IRCC employer portal.

Provincial occupational health and safety legislation

Each province and territory has its own OH&S legislation imposing duties on constructors, employers, and subcontractors. In Ontario, the Occupational Health and Safety Act (OHSA) and Ontario Regulation 213/91 (Construction Projects) place explicit duties on constructors to ensure that every employer and worker on a project complies with the Act and its regulations (Ontario OHSA). In British Columbia, WorkSafeBC's Occupational Health and Safety Regulation applies to all construction workplaces (WorkSafeBC). In Alberta, the OHS Act and OHS Code impose similar duties (Alberta OHS).

Before appointing any subcontractor, the general contractor must satisfy themselves that the organisation has the skills, training, equipment, and organisational capability to carry out the work safely.

Workers' compensation requirements

Provincial workers' compensation boards — WSIB in Ontario, WorkSafeBC in British Columbia, WCB in Alberta — require employers in the construction industry to register and maintain active coverage. General contractors can be held liable for a subcontractor's unpaid premiums and assessed penalties if the subcontractor is not registered or in good standing. Clearance certificates confirm that a subcontractor's workers' compensation account is active and in good standing.

Mandatory documents for construction subcontractors

The table below summarises the core documents that general contractors must collect and verify for each subcontractor operating on Canadian construction sites.

CRA verification: the tax compliance cornerstone

CRA verification of subcontractor status must be completed before engaging any subcontractor. Contractors should verify the subcontractor's Business Number through the CRA's Business Number registry, confirm GST/HST registration, and obtain a completed declaration regarding the subcontractor's independent contractor status.

Common pitfall: the CRA applies a multi-factor test to determine whether a worker is an employee or independent contractor, examining control, ownership of tools, chance of profit/risk of loss, and integration. A subcontractor who works exclusively for one general contractor with no risk of loss and using the contractor's tools may be reclassified as an employee, triggering reassessment for CPP, EI, and income tax source deductions plus penalties.

Workers' compensation clearance certificates

WSIB clearance certificates in Ontario (or equivalent from other provincial WCBs) confirm that a subcontractor's workers' compensation account is in good standing. General contractors should obtain a clearance certificate before making any payment. If the subcontractor's account is not in good standing, the general contractor can be held liable for the subcontractor's unpaid premiums.

WorkSafeBC in British Columbia and the WCB in Alberta have similar clearance certificate requirements. Each province has specific timelines and procedures for obtaining and renewing clearance.

Trade certifications and Red Seal

Compulsory certification trades vary by province. In Ontario, electricians, plumbers, steamfitters, sheet metal workers, and several other trades require a Certificate of Qualification. The Red Seal endorsement, administered through the Interprovincial Standards Program, allows certified tradespeople to practice their trade in any province or territory (Red Seal Program). General contractors must verify that workers in compulsory trades hold valid certifications appropriate to their work.

Workplace safety documentation

Provincial OH&S legislation requires written health and safety policies (for firms above a specified number of employees — 6 or more in Ontario, for example), joint health and safety committees or safety representatives, and site-specific safety plans for construction projects. Documentation of worker training, including WHMIS 2015 training, fall protection certification, and working-at-heights training (mandatory in Ontario), must be available on site.

Penalties for non-compliance

The enforcement landscape for construction subcontractor compliance involves multiple regulators, each with independent penalty powers.

CRA reassessments and penalties

Failure to properly verify a subcontractor's status can result in reassessment for unpaid CPP contributions, EI premiums, and income tax source deductions — plus interest and penalties. Penalties for late or incorrect filings start at 10% of the amount owing and can reach 20% for repeat offences.

Provincial OH&S enforcement

Provincial OH&S inspectors can issue compliance orders (requiring corrective action within a specified timeframe), stop-work orders (halting work immediately), and prosecute under provincial OH&S legislation. Fines for OH&S violations in construction vary by province but can reach CAD 1.5 million or more for corporations in Ontario under the OHSA, with additional penalties under the Criminal Code for criminal negligence.

Workers' compensation penalties

Provincial WCBs can impose premium surcharges, assess contractors for subcontractor premiums, and issue compliance orders. Failure to register with the provincial WCB is an offence that can result in fines and retroactive premium assessments.

Automating subcontractor compliance verification

Managing compliance across a construction supply chain manually is error-prone and resource-intensive. A general contractor working with 30 subcontractors faces approximately 250 document checks per year, each requiring verification of authenticity, validity dates, and scope of coverage.

The case for automation

Manual processes create three structural risks: documents expire between scheduled reviews, forgeries go undetected without systematic authenticity checks, and audit trails are incomplete when stored across emails and shared drives. A single expired WSIB clearance certificate discovered during an inspection can trigger a site shutdown.

Document verification platforms like CheckFile.ai automate the collection, validation, and monitoring of subcontractor compliance documents. Automated expiry alerts, real-time authenticity checks, and centralised audit trails reduce the compliance burden from hours per subcontractor to minutes. Our data from over 180,000 documents processed monthly across regulated sectors confirms a 94.8% fraud detection rate and an 83% reduction in manual review time. View pricing plans designed for construction supply chains.

For a comprehensive overview, see our industry document verification guide.

Frequently asked questions

Do CRA rules apply to labour-only subcontractors?

The CRA applies its multi-factor test to determine whether a worker is an employee or independent contractor regardless of whether materials are provided. Labour-only arrangements are more likely to be reclassified as employment by the CRA, especially where the general contractor controls how, when, and where the work is performed. Contractors should document the factors supporting independent contractor status for each engagement.

Can a general contractor be prosecuted for a subcontractor's health and safety failings?

Yes. In Ontario, the constructor has overarching responsibility for health and safety on a construction project under the OHSA. If the general contractor failed to ensure competent appointment or adequate supervision, they can be prosecuted alongside or instead of the subcontractor. Similar obligations exist in other provinces. The Criminal Code's "Westray" amendments (Bill C-45) also impose criminal liability on organizations and their representatives for workplace safety negligence.

How often should subcontractor compliance documents be reviewed?

WSIB/WCB clearance certificates should be obtained before each contract and verified before each payment. Insurance certificates should be checked at renewal (annually). Trade certifications should be verified at each site induction. Site-specific safety plans should be reviewed before each new project or significant change in scope. As a minimum, a full compliance review of each subcontractor should be conducted every 12 months or at contract renewal, whichever comes first.

What is the difference between WSIB, WorkSafeBC, and other provincial WCBs?

Each province and territory has its own workers' compensation board with distinct registration requirements, premium rates, and clearance certificate processes. WSIB covers Ontario, WorkSafeBC covers British Columbia, and the WCB covers Alberta, among others. General contractors operating in multiple provinces must comply with the requirements of each applicable provincial WCB.

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This article provides general information on construction subcontractor compliance in Canada. It does not constitute legal advice. Consult a lawyer specialising in construction or employment law for advice tailored to your circumstances. Legislation current as of 25 March 2026.

See also: Industry verification guide | Vendor compliance certificate verification | KYB: complete guide to business entity verification

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