Portugal's tax system is structured at national, regional, and municipal levels and is administered by the Tax and Customs Authority (Autoridade Tributária e Aduaneira - AT) via the central Portal das Finanças. Taxes are assessed on a residency basis rather than citizenship, meaning individuals classified as tax residents of Portugal are liable for tax on their worldwide income, while non-residents are taxed only on Portuguese-sourced income. The system features a progressive personal income tax (IRS), corporate income taxes (IRC) which vary regionally, a value-added tax (IVA), and municipal property taxes.