#1. Genesis
N. 1 Art. 134 BV consolidates the harmonisation provisions that were scattered across various norms under the old federal constitution (Art. 32bis para. 5, Art. 36ter, Art. 41bis para. 2 and Art. 41ter para. 2 old FC). According to the Federal Council's message of 20 November 1996 on the new federal constitution, the norm aims at a «formal updating» of the existing legal situation (BBl 1997 I 389). The constitution-maker intended no material change to the established tax order between the Confederation and the cantons.
N. 2 The provision is historically rooted in the gradual expansion of federal competences in the tax area. While the cantons originally had comprehensive tax sovereignty, the Confederation's financing needs led to the successive introduction of federal taxes. With each new federal tax law, the question of delimitation from cantonal levies arose in order to avoid excessive burden on taxpayers.
#2. Systematic Classification
N. 3 Art. 134 BV is found in the third title (Confederation, Cantons and Communes), third section (Financial Order) of the Federal Constitution. The norm supplements the Confederation's tax competences (Art. 128-133 BV) through a negative competence norm in favour of the cantons and communes. It concretises the federalist principle enshrined in Art. 3 BV in the tax area.
N. 4 The provision is closely connected with:
→ Art. 127 para. 2 BV (principles of taxation)
→ Art. 128-133 BV (individual federal taxes)
→ Art. 3 BV (subsidiarity of federal competences)
↔ Art. 127 para. 3 BV (prohibition of intercantonal double taxation)
N. 5 The harmonisation requirement stipulated in Art. 134 BV differs from the prohibition of intercantonal double taxation (Art. 127 para. 3 BV). While Art. 134 BV regulates the vertical relationship between the Confederation on one hand and cantons/communes on the other, Art. 127 para. 3 BV covers the horizontal level between the cantons (→ Art. 127 BV).
#3. Elements of the Offence / Norm Content
N. 6 The elements of Art. 134 BV require three components:
- Federal legislation must designate a tax object
- It must concern value added tax, special consumption taxes, stamp tax or withholding tax
- The cantonal or municipal tax must be «of the same type»
N. 7 Designation by federal legislation: What matters is not the Federal Constitution itself, but the concretising federal legislation. The term «designates» encompasses both the positive description of the tax object and the explicit tax exemption of certain circumstances (BGE 140 I 176 E. 8.2).
N. 8 Federal taxes covered: The enumeration in Art. 134 BV is exhaustive. Notably not covered are direct federal tax and other federal levies. Among the special consumption taxes fall tobacco tax, beer tax, mineral oil tax and automobile tax (Art. 131 BV).
N. 9 Same type: This is the central and most disputed element of the offence. The Federal Court interprets the concept of same type restrictively and focuses primarily on the design of the tax. Case law has developed various delimitation criteria:
- Assessment basis (turnover vs. quantity)
- Collection technique
- Tax subject
- Tax object in the technical sense
#4. Legal Consequences
N. 10 If the elements are fulfilled, cantons and communes are prohibited from levying taxes of the same type. The prohibition is absolute and knows no exceptions. Existing cantonal or municipal taxes become unlawful upon the introduction of a federal tax of the same type and must be repealed.
N. 11 The prohibition only covers taxes in the proper sense, not causal levies such as fees or preferential burdens. The delimitation follows general criteria: taxes are owed without preconditions and serve general state financing, while causal levies compensate for a special counter-performance or special advantage (BGE 140 I 176 E. 3.1).
#5. Controversies
N. 12 Interpretation of same type: Academic opinion is split in its assessment of Federal Court case law:
- Biaggini criticises the practice as canton-friendly or as favouring the treasury more than the citizen, because the cumulation of taxes is merely replaced by coexistence.
- Behnisch rejects the case law that focuses on financial science categories rather than legal-technical criteria. He demands that the Federal Court should abandon its «far too restrictive stance».
- Vallender (StR 1997, 1 ff.) defends the Federal Court's differentiating approach as appropriate.
N. 13 Civil law vs. tax law approach: There is a methodological dispute regarding the delimitation of stamp duties. The Federal Court has opted for a civil law approach and accepted a burden with both taxes. Academic opinion is divided on this:
- Beusch (Commentary StG, Art. 3 N. 15 ff.) supports civil law qualification
- Blumenstein/Locher (System, p. 358) advocate for an economic approach
#6. Practical Guidelines
N. 14 When examining a cantonal or municipal tax for its compatibility with Art. 134 BV, the following procedure should be followed:
- Qualification of the levy as a tax or causal levy
- Examination of whether one of the federal taxes mentioned in Art. 134 BV exists
- Detailed analysis of the technical design of both taxes
- Comparison according to Federal Court criteria
N. 15 Practice shows that identical tax objects do not necessarily lead to same type. What matters is the concrete design. Thus the Federal Court has considered quantity-dependent cantonal alcohol levies as permissible because they differ from turnover-dependent value added tax (Judgment 2P.316/2004 E. 3.2; Judgment 9C_759/2023 E. 2.2).
N. 16 For cantonal legislation, a prior analysis of the technical design of the relevant federal taxes is recommended. Deviations in the assessment basis, collection technique or the circle of taxpayers can justify the permissibility of a cantonal tax. In case of doubt, an alternative design as a causal levy should be examined.