Portuguese corporate income tax has a special feature rarely seen in other countries. Autonomous taxes are levied on an extensive set of corporate expenses, irrespective of corporate profitability. Fiscal revenue from the autonomous taxation of expenses comprises about 12 % of corporate income tax receipts, which illustrates its relevance for the tax authorities and the corporate world. As autonomous tax rules are usually interpreted and applied to certain corporate expenses by chartered accountants (CAs) when computing income tax liabilities and filling in tax returns, the purpose of this paper is to present an empirical study of the perceptions of Portuguese CAs regarding key dimensions of autonomous taxation of expenses (ATE), as these influence corporate tax management. Using a sample of 665 CAs surveyed, and applying factor analysis, the paper concludes that tax complexity, tax compliance and tax planning are the main dimensions of ATE perceived by respondents. Besides the corporate income tax impact on fiscal management, new layers of complexity, planning opportunities and compliance costs are perceived to be added by ATE. Additionally, by applying cluster analysis, the paper finds that sociodemographic characteristics of CAs (e. g. age, gender, professional environment, level of expertise) generate clusters of CAs with different perceptions of the role and consequences of ATE in the management of corporate tax affairs.