The Institute of Chartered Accountants of Ontario is the qualifying and regulatory body of Ontario’s 33,000 Chartered Accountants and 5,000 CA students. Since 1879, the Institute has protected the public interest through the CA profession’s high standards of qualification and the enforcement of its rules of professional conduct. The Institute works in partnership with the other provincial Institutes of Chartered Accountants and the Canadian Institute of Chartered Accountants to provide national standards and programs that are used as examples around the world.

The Institute’s members in public practice are subject to mandatory practice inspection and professional liability insurance programs. These requirements ensure the maintenance and enforcement of high standards that protect the public interest. Other Institute programs support all Ontario Chartered Accountants in fulfilling their professional responsibilities. Among them are a mandatory professional development program, and ethics and technical advisory services.

The Institute also facilitates CA contributions to the wider community. These include such diverse activities as Free CA Tax Clinics for low-income people and providing government with technical advice on a wide range of provincial legislative matters.

The profession of Chartered Accountancy in Ontario is governed by the Chartered Accountants Act. Public accountancy (activity that lends credibility to financial statements) is governed in Ontario by the Public Accounting Act, 2004. Standards of practice are enforced by the Institute's Rules of Professional Conduct and bylaws. Oversight is provided by the Public Accountants Council, which has authorized the Institute to serve as a public accounting licensing body.

Ontario CAs work in public practice, industry, education, government and the not-for-profit sector, and serve every facet of society. They contribute greatly to international and domestic investor confidence in the soundness of the Ontario and Canadian economies.