Based in Lausanne, Switzerland, Atca is a fiduciary firm offering many tailor-made services in accounting, tax, auditing and consulting. Created in 2016, Atca is a fiduciary firm comprising a multilingual team of accountants, offering its services to medium-sized companies.Based in Lausanne, Switzerland, Atca is a fiduciary firm offering many tailor-made services in accounting, tax, auditing and consulting. Created in 2016, Atca is a fiduciary firm comprising a multilingual team of accountants, offering its services to medium-sized companies.