1Der Bund kann für grosse Unternehmensgruppen Vorschriften über eine Besteuerung im Marktstaat und eine Mindestbesteuerung erlassen.
2Er orientiert sich dabei an internationalen Standards und Mustervorschriften.
3Er kann zur Wahrung der Interessen der schweizerischen Gesamtwirtschaft abweichen von:
a.
den Grundsätzen der Allgemeinheit und der Gleichmässigkeit der Besteuerung sowie dem Grundsatz der Besteuerung nach der wirtschaftlichen Leistungsfähigkeit gemäss Artikel 127 Absatz 2;
b.
den maximalen Steuersätzen gemäss Artikel 128 Absatz 1;
c.
den Vorschriften über den Vollzug gemäss Artikel 128 Absatz 4 erster Satz;
d.
den Ausnahmen von der Steuerharmonisierung gemäss Artikel 129 Absatz 2 zweiter Satz.
Art. 129a BV authorises the Confederation to tax large corporations with a minimum tax of 15 percent. This new tax applies to corporate groups with an annual turnover of at least 750 million euros.
The provision arose through international agreements of the OECD and G20. Without this new tax, other countries could have taxed Swiss corporations. The Swiss people voted on 18 June 2023 with 78.5 percent in favour of this constitutional amendment.
The minimum tax functions as a supplementary tax. If a large corporation pays less than 15 percent profit tax in Switzerland, it must pay the difference. A corporation with a 10 percent tax burden pays an additional 5 percent to reach 15 percent. Normal taxation remains in place.
Only about 150 to 200 large corporate groups are affected by the new tax. Small and medium-sized enterprises (SMEs) remain completely exempt. The cantons implement the tax, based on international standards.
The Confederation may deviate from certain constitutional principles with this tax. For example, it may tax different enterprises differently, which would normally be prohibited due to the principle of equality.
The expected tax revenue amounts to approximately 1 to 2.5 billion francs per year. Three quarters go to the cantons, one quarter to the Confederation. The cantons shall use their shares for location promotion.
Art. 129a BV entered into force on 1 January 2024. The first taxes will be levied from 2025 for the 2024 financial year.
N. 1 Art. 129a BV was adopted by the people and the cantons on 18 June 2023 with 78.5% of yes votes and entered into force on 1 January 2024. The provision stems from the international agreement within the OECD and G20 framework for the introduction of a global minimum tax for large multinational enterprise groups (OECD/G20 Inclusive Framework on BEPS, Pillar Two).
N. 2 On 22 June 2022, the Federal Council submitted to Parliament the Federal Council Dispatch on the Amendment of the Federal Constitution (Introduction of an OECD Minimum Tax for Large Enterprise Groups) (BBl 2022 1598). The constitutional amendment was necessary because the existing constitutional order did not grant the Confederation competence to levy such a supplementary tax.
N. 3 Parliamentary deliberation took place through expedited proceedings. The National Council and Council of States approved the proposal in the final vote of 16 December 2022 with overwhelming majorities (National Council: 170:11 votes, Council of States: 40:2 votes). This reflects the broad political consensus on securing the international acceptance of the Swiss tax system.
N. 4 Art. 129a BV is systematically classified in Title 3 (Confederation, Cantons and Communes), Chapter 3 (Financial System), Section 1 (General Provisions). The provision supplements the existing tax competences of the Confederation under Art. 128-134 BV with a special, purpose-bound taxation competence.
N. 5 Unlike traditional federal taxes (direct federal tax under Art. 128 BV, value added tax under Art. 130 BV), the minimum tax under Art. 129a BV is a supplementary tax with international connection. It only applies insofar as ordinary taxation does not reach the 15% threshold (→ Art. 128 BV).
N. 6 The provision shows a close connection to Art. 94 BV (Principles of Economic Policy) and Art. 100 BV (Economic Policy), as it is intended to secure the competitiveness of Switzerland as a business location in international tax competition. There is also a connection to Art. 5a BV (Subsidiarity), as implementation takes place primarily through the cantons.
N. 7Large Enterprise Groups: The concept is not constitutionally autonomous but refers to the international OECD standards. According to these, enterprise groups with a consolidated annual revenue of at least 750 million euros are considered "large". The threshold corresponds to the Country-by-Country Reporting standard.
N. 8Minimum Tax of 15 Percent: The Constitution fixes the minimum tax rate at 15%. This refers to the effective tax rate, not the nominal tariff. Decisive is the total burden from profit taxes of all state levels (Confederation, cantons, communes).
N. 9Taxation of Profit: The minimum tax is exclusively linked to profit, not to other assessment bases such as capital or revenue. The concept of profit is governed by the international GloBE rules (Global Anti-Base Erosion Rules), which are based on accounting standards.
N. 10 The constitutional provision establishes a federal competence for minimum taxation. This encompasses both legislation and enforcement, whereby the cantons are to be involved "as far as possible" according to para. 1 sentence 2. This corresponds to cooperative federalism (→ Art. 46 BV).
N. 11Supplementary Tax: If the effective tax burden of a group entity resident in Switzerland is below 15%, the difference must be levied as a supplementary tax. This tax is in addition to ordinary taxation and does not replace it.
N. 12International Coordination: Switzerland can also apply the minimum tax to foreign group entities if their state of residence does not provide equivalent taxation (so-called Undertaxed Profits Rule). This prevents other states from accessing Swiss group companies.
N. 13Federalist Implementation: In the consultation, it was disputed whether implementation should be central through the Confederation or decentralized through the cantons. The Conference of Cantonal Finance Directors (FDK) successfully advocated for a cantonal solution with a federal framework law (BBl 2022 1598, 1611 f.).
N. 14Use of Additional Revenue: The distribution of expected additional revenue was controversially discussed. The constitutional text leaves this open. In parliamentary debate, the Confederation and cantons agreed on a division of 25% (Confederation) to 75% (cantons), whereby the cantons should use their shares for location promotion (AB 2022 N 1766 ff.).
N. 15Relationship to Double Taxation Agreements: The relationship of the minimum tax to existing double taxation agreements remains unclear. The prevailing doctrine holds that OECD minimum taxation, as a multilaterally coordinated measure, does not violate bilateral DTAs (Matteotti/Roth, ASA 91 (2022/23), 417, 425 ff.).
N. 16Threshold Assessment: Enterprise groups must annually assess whether they exceed the revenue threshold of 750 million euros. Two of the last four business years are decisive. Special rules apply for restructuring.
N. 17Effective Tax Burden: The calculation of the effective tax burden is conducted on a jurisdictional basis according to the complex GloBE rules. Companies should implement systems for data collection and calculation at an early stage.
N. 18Location Attractiveness: Cantons can maintain their location attractiveness through non-tax measures (subsidies, infrastructure, education) or by reducing ordinary profit tax rates for unaffected companies. The minimum tax only applies to large corporations; SMEs remain unaffected.
At present, there is no established case law regarding Art. 129a Cst. The provision was only adopted in a referendum on 18 June 2023 and entered into force on 1 January 2024. The first applications will arise in the course of implementing the OECD/G20 minimum taxation from 2024 onwards.
Cantonal voting rights appeal concerning tax law revision in the Canton of Lucerne for implementing the OECD minimum taxation. The Federal Supreme Court examined the political rights in the voting procedure without deciding substantively on the constitutional provision. The appellants alleged incomplete information about municipal revenues from the OECD minimum taxation.
«to clarify that the municipal share of revenues from the OECD minimum taxation according to the tax law revision amounts to merely CHF 26.6 million or CHF 23.5 million from 2030»
The proceedings demonstrate the practical significance of the constitutional provision for cantonal legislation and the distribution of finances between the Confederation, cantons and municipalities.
The substantive case law on Art. 129a Cst. will develop as soon as concrete disputes arise concerning the delineation of federal competences, the interpretation of the minimum tax of 15 percent and the distribution of tax revenues. Relevant issues will particularly concern the compatibility of cantonal implementing laws with the constitutional provision as well as coordination with international agreements.