Article 102 (Bank of Portugal) The Bank of Portugal is the national central bank and shall exercise its functions as laid down by law and in accordance with the international norms by which the Portuguese state is bound. Article 103 (Fiscal system) 1. The fiscal system shall aim to satisfy the financial needs of the state and of other public entities and to ensure a just distribution of income and wealth. 2. Taxes shall be created by laws, which shall lay down their applicability and rate, fiscal benefits and the guarantees accorded to taxpayers. 3. No one shall be obliged to pay taxes that are not created in accordance with the Constitution, are retroactive in nature, or are not charged and collected as laid down by law. Article 104 (Taxes) 1. Personal income tax shall aim to reduce inequalities, shall be single and progressive and shall pay due regard to the needs and incomes of households. 2. Enterprises shall essentially be taxed on their real income. 3. The taxation of assets must contribute to equality between citizens. 4. The taxation of consumption shall aim to adapt the structure of consumption to evolution in the requirements for economic development and social justice, and must increase the cost of luxury consumer items. Article 105 (Budget) 1. The State Budget shall contain: a) A breakdown of the state’s income and expenditure, including that of autonomous funds and departments; b) The social security budget. 2. The Budget shall be drawn up in harmony with the major planning options and in the light of legal and contractual obligations. 3. The Budget shall be a single budget and shall set out expenditure in accordance with the respective organisational and functional classification, in such a way as to preclude the existence of secret appropriations and funds. It may also be structured by programmes.