Introduction

Architects and landscape architects in Ontario are permitted to practise through professional corporations — but the rules governing those corporations are specific to the profession and distinct from the general rules that apply to any other incorporated business.

This article explains how professional corporations work for architects in Ontario, when incorporation makes financial sense, and what the CPAO (College of Architects of Ontario) and the Income Tax Act together require.

Can Architects Incorporate in Ontario?

Yes. The Architects Act (Ontario) and associated regulations permit architects to practise through a professional corporation, provided the corporation meets specific requirements set by the Ontario Association of Architects (OAA) and is authorised to practise architecture.

Not all design professionals qualify for professional corporation status. Interior designers, industrial designers, and landscape architects operate under different regulatory frameworks. Architects licensed by the OAA specifically are the group for whom the professional corporation structure described in this article applies.

The Tax Case for Incorporation

As with other incorporated professionals, the primary tax advantage for an architect operating through a professional corporation is the deferral of personal tax on income retained in the corporation.

An architect earning $300,000 per year who draws only $150,000 personally can retain the remaining after-tax corporate profit inside the corporation, paying corporate tax at the small business rate (approximately 12.2% combined in Ontario in 2026) on income up to $500,000, rather than personal tax at marginal rates of up to 53.53% in Ontario.

The retained earnings can then be invested inside the corporation, compounding at a higher after-tax base than would be available had the income been fully drawn personally. Over a career, the compounding effect of this deferral is significant.

The tax case for incorporation strengthens as income grows. For architects earning below $100,000–$120,000, the administrative cost of maintaining a corporation may outweigh the tax benefit. Above that range — and particularly for architects earning consistently above $200,000 — incorporation is typically worth the complexity.

Professional Corporation Requirements Under the OAA

The OAA has specific requirements for professional corporations. These include:

•  The corporation must hold a Certificate of Practice issued by the OAA

•  A majority of voting shares must be held by licensed architects (members in good standing of the OAA)

•  The corporation must carry on only the practice of architecture and ancillary activities

•  The corporation's name must comply with OAA naming requirements

•  Directors and officers who practise architecture must be licensed

These requirements are in addition to general Ontario corporate law requirements and CRA registration obligations. A corporation that does not comply with OAA requirements is not validly authorised to practise architecture through the corporate form.

Non-Voting Shares and Income Splitting

Non-voting shares of an architect's professional corporation can, in principle, be held by family members — providing a mechanism for dividend income to be paid to family members in lower tax brackets. However, the TOSI (tax on split income) rules significantly restrict when this income splitting is effective, as discussed in Rotaru CPA's earlier articles. The practical opportunity for income splitting through a professional corporation is more limited than it was before 2018.

Transitioning an Existing Practice to a Corporation

For an architect who has been practising as a sole proprietor or in a partnership and is considering incorporation, the transition involves:

•  Incorporating the professional corporation and obtaining OAA authorisation

•  Transferring the practice's assets and engagements to the new corporation (with attention to client notification requirements)

•  Setting up payroll, HST accounts, and corporate bookkeeping

•  Addressing any WIP and receivables that straddle the transition date

The transition year requires careful planning to ensure income is allocated correctly between the pre-incorporation personal period and the post-incorporation corporate period.

When to Speak With a CPA

The decision to incorporate — and the mechanics of doing so correctly — benefit from CPA input alongside legal advice. A CPA can model the tax savings at the specific income level, advise on the right timing, and ensure the new corporate structure is set up for compliance from day one.

Rotaru CPA works with architects in Ontario on professional corporation setup and ongoing tax compliance. Book a consultation to discuss whether incorporation makes sense for your practice.