Switzerland’s 15% top-up tax in 2026: first returns, safe harbours and who gets the money

Country reference

• Country: Switzerland (Wave 1 expansion country)
• Authorities: Federal Tax Administration (FTA); Federal Department of Finance (FDF); cantonal tax administrations
• Topic: Top-up tax for large multinational groups under the OECD/G20 minimum tax
• Key date: FTA communications of 7 April 2026; first Swiss top-up tax returns due 30 June 2026
• Law: Federal Constitution (vote of 18 June 2023); Minimum Taxation Ordinance

The rules in brief

• Groups with consolidated annual turnover of at least EUR 750 million are in scope.
• Where the effective tax rate is below 15%, Switzerland charges the difference as a top-up tax.
• Swiss top-up tax (a qualified domestic minimum top-up tax) has applied since 1 January 2024.
• International top-up tax (the income inclusion rule) has applied since 1 January 2025, after the Federal Council’s decision of 4 September 2024.
• Switzerland has not introduced the undertaxed profits rule.

What happened in 2026

• 5 January: the OECD Inclusive Framework agreed the Side-by-Side Package of new safe harbours.
• 7 April: the FTA published two communications. One covers the temporal application of the Side-by-Side Package and how elections are exercised. The other covers the guidance on Article 9.1 of the model rules, which limits the use of certain deferred tax assets.
• 30 June: first Swiss top-up tax returns were due, according to adviser commentary.
• Returns and registration go through the federal ePortal.

Where the money goes

• 75% of top-up tax receipts go to the cantons and 25% to the Confederation.
• The first receipts arrive in 2026. The federal financial plan assumes CHF 400 million a year for the Confederation and CHF 1.2 billion for the cantons.
• In its 2027 budget release the Federal Council called these estimates very uncertain.

Legal footing

Voters approved the constitutional basis on 18 June 2023 with 78.5% in favour. The tax runs on an ordinance for now. The Federal Council must send Parliament a federal act within six years of the ordinance taking effect.

What to do now

• Check which safe harbours the group can elect for financial years starting in 2026, and document the election.
• Review deferred tax assets against the Article 9.1 guidance before finalising returns.
• Confirm ePortal access and who files for each Swiss entity.

Our take

Several cantons have set up or announced location support funded from their share, so the top-up tax is changing the Swiss offer, not ending it. Groups with a Swiss principal company should model the safe harbours before assuming a top-up payment, and should ask their canton what support is available.