Book Consultation

Gondaliya CPA

Gondaliya CPA Professional Corporation logo
100% Canadian Owned badge
Menu
Construction Audit Guide · Ontario · Licensed CPA

Construction Audit Preparation: What the CRA and WSIB Look For

Why the CRA audits construction more than almost any other industry, the T5018 and subcontractor data that triggers it, the WSIB clearance trap that makes you liable for someone else's premiums, what an auditor asks for, and how to be ready before the letter arrives. Written by a licensed Canadian CPA who works with contractors.

Book Free ConsultationKnow Exact Fees within 2 Minutes

Construction is one of the most audited industries in Canada. The CRA runs a dedicated construction compliance program that matches your T5018 subcontractor slips against what those subcontractors report, flags cash-heavy operations, and targets worker misclassification. WSIB audits your insurable earnings separately. Being ready means clean job-costed books, filed T5018s, WSIB clearance certificates on every subcontractor, and an invoice behind every expense, kept as you go rather than reconstructed after the letter arrives.

Why Construction Gets Audited More Than Almost Anything

It is not bad luck. The CRA treats construction as a high-risk sector and runs a dedicated compliance program aimed at it, because the industry has the features tax authorities watch most closely: heavy subcontracting, cash and cheque payments, project-based revenue that spans tax years, and a long history of unreported labour. The result is that a contractor faces a materially higher chance of review than most other businesses of the same size.

The good news is that the triggers are known and the preparation is concrete. An audit is a records exercise, and a contractor with clean, job-costed books and complete documentation has little to fear from one. For the wider picture please see our construction CPA services.

What Actually Triggers a Construction Audit

Most construction audits start from a data mismatch, not a random draw. These are the patterns that put a contractor's file on an auditor's desk.

TriggerWhat the CRA Sees
Missing or late T5018Subcontractor payments deducted but never reported on the required slips
T5018 mismatchYour slip amounts do not match what the subcontractor reported as income
Worker misclassificationPeople treated as subcontractors who look like employees
Cash-heavy operationsDeposits and deductions that do not reconcile to reported revenue
Late payroll remittancesA pattern of missed or late source-deduction remittances
T4 and remittance mismatchT4 totals that do not agree with what was remitted
WSIB and CRA data discrepancyInsurable earnings reported to WSIB that do not match payroll

The T5018 is the single biggest trigger in construction. The CRA matches contractor slips against subcontractor tax returns, so a missing slip, a late filing, or a number that does not match the subcontractor's reported income is exactly the kind of discrepancy the construction compliance program is built to find. Please see our WSIB compliance guide.

The Three Audits a Contractor Can Face

"Construction audit" is not one thing. A contractor can be reviewed on three separate fronts, sometimes at once, and each looks at different records.

AuditWhoWhat They Examine
Income tax (T2)CRARevenue, subcontractor and material costs, equipment, vehicle claims, T5018
GST/HSTCRAHST collected on progress billings, input tax credits, holdback timing
PayrollCRASource deductions, remittances, T4s, worker classification, per diems
Insurable earningsWSIBPremiums, classification codes, clearance certificates on subcontractors

A single problem often surfaces in more than one of these. A subcontractor recharacterised as an employee, for example, hits your income tax, your payroll and your WSIB position at the same time. Please see our subcontractor versus employee guide.

The WSIB Clearance Trap

This is the construction-specific exposure most contractors underestimate. WSIB coverage is mandatory in construction, with no opt-out, and a general contractor must obtain a valid WSIB clearance certificate from every subcontractor before releasing final payment. Skip it, and if that subcontractor was uninsured, the contractor's own WSIB account can absorb their unpaid premiums and any claim.

A missing clearance certificate is a bill waiting to happen. Paying a subcontractor who has no valid WSIB coverage makes you liable for their premiums, and a WSIB audit will look for exactly this. Collecting a clearance certificate before final payment, every time, is one of the cheapest pieces of audit protection in the industry. See our WSIB compliance guide.

What an Auditor Will Ask You For

An audit is a request for records. The specific documents vary with the type of review, but for a construction file the list is predictable, which is precisely why it can be prepared in advance.

DocumentWhy the Auditor Wants It
T5018 slips and summaryTo match subcontractor payments against reported income
Subcontractor invoices and contractsTo test whether subs are genuinely independent, not employees
WSIB clearance certificatesTo confirm every sub was covered before final payment
Job-costing recordsTo trace revenue and costs to specific projects
Bank statements and depositsTo reconcile deposits against reported revenue
Vehicle logbooksTo support the business-use percentage claimed
Equipment purchase recordsTo confirm capital cost allowance classes and timing
Payroll records and T4sTo reconcile remittances and check per-diem treatment

An expense with no invoice behind it is not supportable. A bank statement shows that a payment left the account, not what it bought. In a construction audit, cash paid to trades with no invoice is the first thing disallowed, so the invoice, not the bank line, is what protects the deduction. Please see our construction bookkeeping.

How to Be Ready Before the Letter Arrives

Audit preparation is not something you do when the letter comes; by then your position is already fixed by the records you kept. Real preparation is the system you run all year.

  1. File your T5018s correctly and on time. Every subcontractor paid for construction services, reported on the summary within six months of your fiscal year end, with amounts that match what you actually paid.
  2. Collect a WSIB clearance certificate from every sub. Before final payment, every time, and keep it on file. This closes the single most common WSIB exposure.
  3. Classify every worker deliberately. Confirm whether each person is a subcontractor or an employee on the facts, and keep the contracts and evidence that support the treatment.
  4. Job-cost as you go. Trace materials, subtrades, permits and site costs to the jobs that caused them, so revenue and cost reconcile project by project.
  5. Keep an invoice behind every expense. Digital copies are fine if complete and readable, kept for six years. Reconstructing after a review begins costs far more and convinces far less.

What Happens During and After the Audit

An auditor requests records, tests them, and proposes adjustments. You have the right to respond before anything is finalised, and how the file is handled at this stage matters enormously. Explaining a job-costing method or documenting a subcontractor relationship well can be the difference between a clean result and a reassessment. If adjustments are proposed, they can be disputed through the objection process. Facing a construction audit with representation, rather than alone, generally produces a materially better outcome, because the issues are technical and the way they are presented affects the result.

Case Study: General Contractor, Ontario

A contractor received a CRA letter opening a review after several years of paying a dozen subtrades annually without ever filing a T5018, while also claiming the owner's truck at 100% with no logbook and leaving all costs in a single overhead account. Left unaddressed, the file was heading for a reassessment across multiple years plus penalties, and a parallel WSIB exposure because clearance certificates had never been collected. We brought the T5018 filings current, reconstructed defensible job-costing and vehicle records, gathered the subcontractor contracts and the clearance certificates that could still be obtained, and dealt with the auditor directly on the contractor's behalf. The classification of the subtrades held, the vehicle claim was rebuilt on a supportable percentage, and the exposure was reduced to a fraction of where it started. The figures here are illustrative of the work we do, not a specific client file.

T5018 brought current. Classification held. Exposure cut to a fraction of the opening position.

Facing a Construction Audit, or Want to Be Ready Before One?

We prepare your records, deal with the auditor directly, and fix the exposures before they cost you. AFFORDABLE flat fees from $150/month. All fees include HST.

Book Free Consultation

Frequently Asked Questions: Construction Audit Preparation

Why is construction audited more than other industries?
Because the CRA treats it as high-risk and runs a dedicated construction compliance program. The industry has the features tax authorities watch most: heavy subcontracting, cash and cheque payments, project revenue spanning tax years, and a history of unreported labour. A contractor faces a materially higher chance of review than most other businesses of the same size.
What triggers a CRA construction audit?
Usually a data mismatch, not a random draw. The most common triggers are a missing or late T5018, slip amounts that do not match what the subcontractor reported, worker misclassification, cash-heavy operations that do not reconcile to revenue, late payroll remittances, T4-to-remittance mismatches, and WSIB earnings that differ from payroll.
What is the T5018 and why does it matter for audits?
The T5018, Statement of Contract Payments, reports the amounts you paid to subcontractors for construction services. The CRA matches your slips against those subcontractors' tax returns, so a missing slip or a mismatched amount is exactly the discrepancy the construction compliance program is built to catch. It is the single biggest audit trigger in the industry.
When is the T5018 due?
Within six months of your fiscal year end. You report each subcontractor paid for construction services on a slip, with a summary, and the amounts must match what you actually paid. You choose either a calendar-year or fiscal-year basis and must stay consistent, since changing periods without approval creates gaps that draw CRA inquiries.
Do I have to file a T5018 for every subcontractor?
For subcontractors paid for construction services where construction is your principal business activity, broadly more than half your income. Payments purely for materials or goods do not count, non-resident subcontractors go on a T4A-NR, and employees go on a T4, not a T5018. Amounts under $500 in the year are generally not reportable.
What is the WSIB clearance certificate trap?
WSIB coverage is mandatory in construction with no opt-out, and a general contractor must obtain a valid clearance certificate from every subcontractor before releasing final payment. Pay a sub who has no valid coverage and your own WSIB account can absorb their unpaid premiums and any claim. A WSIB audit looks for exactly this. See our WSIB compliance guide.
What are the three or four audits a contractor can face?
Income tax on the T2, GST/HST, and payroll, all from the CRA, plus a WSIB audit of insurable earnings. Each examines different records, and a single issue often surfaces in more than one. A subcontractor recharacterised as an employee, for example, affects your income tax, your payroll and your WSIB position at once.
What documents will a construction auditor ask for?
Typically your T5018 slips and summary, subcontractor invoices and contracts, WSIB clearance certificates, job-costing records, bank statements and deposits, vehicle logbooks, equipment purchase records, and payroll records and T4s. The list is predictable, which is why a well-run contractor can prepare for it in advance.
What is worker misclassification and why is it a top trigger?
It is treating someone as a subcontractor when the facts make them an employee. The CRA weighs control, whether the company directs the methods, hours and location, against economic dependence, whether the worker has multiple clients, their own equipment and real financial risk. The contract title is irrelevant. Misclassification affects income tax, payroll and WSIB together.
How does the CRA decide if my worker is a subcontractor or employee?
It examines the whole relationship. Control over how, when and where the work is done points to employment; multiple clients, ownership of tools and equipment, and genuine financial risk point to an independent subcontractor. No single factor decides it, and calling someone a subcontractor in a contract does not make them one. See our CRA audit resolution services.
Can cash payments trigger an audit?
Yes. Construction runs heavily on cash and cheques, which automatically raises CRA attention, and deposits or deductions that do not reconcile to reported revenue are a classic trigger. Cash paid to trades with no invoice is the first thing disallowed in an audit, so every cash payment needs documentation behind it.
What happens if I never filed T5018 slips?
The CRA can assess late-filing penalties, deny or question the subcontractor deductions, and open a broader review, because unreported subcontractor payments are treated as a red flag for unreported cash labour. The fix is to bring the filings current, ideally before the CRA raises it. See our catch-up filing.
How do I prepare for a construction audit before it happens?
Run the system all year: file T5018s correctly and on time, collect a WSIB clearance certificate from every sub before final payment, classify every worker deliberately with supporting contracts, job-cost as you go, and keep an invoice behind every expense for six years. By the time a letter arrives, your position is already set by the records you kept.
What is job costing and why does an auditor care?
Job costing traces materials, subtrades, permits and site costs to the specific projects that caused them, so revenue and cost reconcile project by project. Auditors use it to test that revenue is complete and costs are real. A contractor who lumps everything into one overhead account cannot answer basic audit questions, which extends and worsens the review.
Are per diems a construction audit issue?
Yes. Meal and travel allowances paid to workers away from the employer's municipality are not taxable up to the CRA's daily line, but any excess is a taxable benefit that belongs on the T4 with CPP, EI and tax. Per diems left off T4s are a common construction payroll audit finding. We handle the treatment correctly.
What records support my vehicle and equipment claims?
A logbook supporting the business-use percentage of a vehicle, and purchase records confirming the capital cost allowance class and timing for equipment. In an audit, the CRA can deny an entire vehicle or equipment deduction where no contemporaneous log or record exists, so these are exactly the documents to keep as you go.
What is the penalty if a construction audit goes badly?
Depending on the issue, reassessed tax across multiple years, interest, and penalties, plus separate WSIB premium exposure where clearance certificates were missing. Where amounts were misreported the CRA can add a gross negligence penalty. Across several years and several subs the exposure compounds, which is why proactive preparation is so much cheaper.
Can you help if I have already received an audit letter?
Yes. We review what the CRA has asked for, prepare and organise the records, deal with the auditor directly on your behalf, and where adjustments are proposed we dispute them through the objection process. Facing a construction audit with representation generally produces a materially better outcome than facing it alone. See our CRA audit resolution.
What is the CRA Construction Compliance Initiative?
It is the CRA's dedicated program targeting the construction sector, using T5018 data alongside licence records, GST/HST registration files, permit lists and labour cost-to-revenue benchmarks to identify unreported income and mismatched claims. It is why construction files are reviewed at a higher rate, and why clean T5018 reporting matters so much.
Do I need to worry about the T4A change for 2026?
Possibly. The long-standing moratorium on penalties for failing to report fees for service in T4A Box 048 is ending, so from 2026 you must prepare and file T4A slips for non-construction service contractors paid over $500 in the year. Construction service payments still go on the T5018. We make sure the right slip is filed for each type of payment.
Can a WSIB audit and a CRA audit happen together?
They are separate, but they feed each other. WSIB and the CRA compare data, so insurable earnings reported to WSIB that do not match your payroll can trigger questions on both sides. A worker misclassification found by one is often picked up by the other. Preparing your payroll and subcontractor records cleanly protects you on both fronts.
How long should I keep construction records?
At least six years from the end of the tax year they relate to. That covers contracts, subcontractor invoices, T5018 records, clearance certificates, job-costing detail, bank statements, logbooks and payroll. Digital copies are acceptable if complete and readable. Keeping them organised as you go is what makes an audit a records exercise rather than a crisis.
What if the CRA issued an arbitrary assessment because I did not file?
Arbitrary assessments are almost always inflated because the CRA estimates high. We replace the estimate with your actual project revenue, job costs and subcontractor expenses, file the real returns, and pursue penalty relief where the delay was beyond your control, which usually reduces the balance substantially. See our catch-up filing.
Does holdback affect my audit exposure?
Yes. Holdback and progress billing create revenue-timing questions, since HST is generally due when the invoice is issued and holdback income must be reported in the correct fiscal year under the Construction Act timeline. Misreporting the timing is a common reassessment area, so holdback needs to be tracked precisely.
Can I fix past construction filing problems before an audit?
Yes, and it is far cheaper than waiting. If T5018s are missing, HST was mishandled, or classification was wrong, we correct the records and bring the filings current, and where you come forward before the CRA contacts you, penalty relief through the Voluntary Disclosure Program may be available. See our past account clean-up.
How much does construction audit support cost?
Audit preparation and support are part of our construction accounting work, from $150 per month, quoted as a flat fee upfront with no hourly billing, and CRA audit support is included for our ongoing clients. All fees include HST. Please use our pricing calculator for an exact figure.
Do you work with contractors across Ontario?
Yes. We are a licensed Ontario CPA firm working with general contractors, subcontractors, builders and trades across Ontario and Canada, virtually. Everything is handled through our secure portal, so your location is never a constraint.
How do I get started?
Please book a free consultation and tell us about your business, roughly how many subtrades you pay, whether your T5018s are filed, and whether you have received any CRA or WSIB correspondence. We review your exposure, prepare your records, and quote an exact flat fee. Book Free Consultation →

What Our Clients Say

1300+ five-star reviews from contractors and business owners across Ontario and Canada.

Audit-Ready Contractors Sleep Better. We Get You There.

We file your T5018s correctly, keep your subcontractor and WSIB records clean, prepare your books for any review, and deal with the auditor directly if a letter arrives. AFFORDABLE flat fees from $150/month, CRA audit support included for clients. All fees include HST.

Scroll to Top