About Us: Peterson Sullivan is a leading local public accounting and business advisory firm based in Seattle, Washington. They are ranked among the top 10 largest CPA firms in the Puget Sound region, with more than 190 professionals and support staff. Peterson Sullivan serves clients in many industries including dealerships, nonprofit, real estate, construction, hospitality, financial services, technology, life sciences and professional services – providing assurance, tax, business valuations and litigation support services. For 65 years, Peterson Sullivan has helped clients maximize their value.