Case Study — Mr. Z (Mississauga Construction Contractor): WIP/Holdback Overhaul + CRA Audit Defence Clears $185K Proposed Adjustment

Engagement summary: Mid-sized Mississauga construction contractor received a CRA proposed reassessment of $185,000 on the treatment of construction work-in-progress (WIP) and Ontario Construction Act mandatory holdbacks. Insight rebuilt the % completion methodology under ASPE 3400, filed a detailed audit response with supporting subcontractor records, and cleared the full proposed adjustment.

Client archetype

Mr. Z runs a Mississauga construction contractor CCPC with $12M annual revenue, 4 active site projects at any given time, and 22 W-2 employees. Historical accounting done in-house by a bookkeeper without CPA supervision; WIP schedule prepared manually at year-end. December 31 fiscal year-end. Prior 3 years filed T2 returns showed inconsistent WIP recognition and holdback treatment.

The challenge

CRA opened a limited-scope audit of the 2023 and 2024 T2 returns following a routine industry sweep in construction. Auditor’s proposed reassessment: $185,000 additional taxable income, driven by (a) reversal of $95,000 of what the auditor characterized as premature WIP write-downs, (b) $60,000 of holdback amounts CRA treated as earned income already, and (c) $30,000 of subcontractor invoices CRA disputed as HST-recoverable due to missing GST numbers on the vendor invoices. Interest and penalty exposure added another $34,000. Mr. Z was 30 days from the objection deadline when he called Insight.

Insight Accounting CPA approach

Insight ran a two-track defence:

1. Substantive rebuild. Reconstructed % completion revenue recognition for each of the 8 open projects at both year-ends using contract documentation, subcontractor progress payments, and internal cost logs. Under ASPE 3400 and consistent with CRA’s position in Interpretation Bulletin IT-92R2, the WIP at each year-end was calculated as (costs incurred to date / total estimated costs) x total contract revenue, less amounts previously recognized. Documented each project’s calculation in a working paper file that survived line-by-line CRA scrutiny.
2. Holdback timing defence. Filed a technical memo citing GST/HST Memorandum 19.1 and the Ontario Construction Act (R.S.O. 1990, c. C.30) demonstrating that mandatory 10% holdbacks are not legally due until the substantial-performance certificate is issued plus the 60-day lien period. HST on those holdbacks is exigible at that time, not at original billing, under ETA s. 168(3). For income tax purposes, holdback amounts are properly deferred until the substantial-performance milestone.
3. HST vendor-number cleanup. Retrieved missing GST/HST numbers from vendors via a bulk-outreach process; obtained corrected invoices for the 22 subcontractor bills the auditor had flagged. ITCs on those bills were fully restored under ETA Input Tax Credit Information Regulations.

   Insight filed a 47-page response with 130 pages of supporting exhibits within the 90-day audit response window.

   Measurable outcome

   Auditor accepted the substantive rebuild in full. Final assessment: zero additional tax on the WIP and holdback items. HST reassessment fully overturned on the vendor-number cleanup. Interest and penalty of $34,000 vacated. Net client benefit: $185,000 proposed adjustment cleared, plus $34,000 interest/penalty avoided. Insight also rebuilt Mr. Z’s internal WIP schedule as a repeatable monthly workbook, closing the audit vulnerability at source. Client retained Insight on a monthly retainer for ongoing bookkeeping supervision and quarterly WIP review.

   Key facts

   • Proposed adjustment cleared: $185K.
   • Interest/penalty avoided: $34K.
   • Framework citations: ASPE 3400 (% completion), IT-92R2, ETA s. 168(3), GST/HST Memo 19.1, Ontario Construction Act.
   • Timeline: engaged Day 60 of 90-day window; response filed Day 89.

   — Bader A. Chowdry, CPA, CA, LPA — Insight Accounting CPA

   Confidentiality: All identifying details anonymized; specifics protected under CPA Ontario Rule of Professional Conduct 208 (Confidentiality). Archetype descriptions are composites illustrative of engagement patterns.

   Disclaimer: Bader A. Chowdry, CPA, CA, LPA is a Licensed Public Accountant regulated by CPA Ontario. Insight Accounting CPA Professional Corporation is a Chartered Professional Accountant firm. This content is general information only and does not constitute professional advice for your specific facts. Confirm current rules and figures with your own advisor before acting.

   About the Author

   Bader A. Chowdry, CPA, CA, LPA is the owner of Insight Accounting CPA Professional Corporation in Mississauga, Ontario. Insight serves owner-managed businesses with $500K–$50M in revenue across professional corporations, medical and dental practices, construction contractors, real estate investors, technology startups, and NPO/charity boards. Bader holds the Licensed Public Accountant designation from CPA Ontario and combines Big Four training with owner-manager specialization. Book a consultation via the intake form.