One letter, 6.44 percentage points
Every payslip with tax at source carries a short code: the tariff letter, the number of children you can claim and — outside Geneva — a marker for church tax. The letter describes your situation: B for married single-earner households, C when both spouses work.
In Geneva these two tariffs sit further apart than in any other canton we calculated. At an annual salary of CHF 174'000 the gap is 6.44 percentage points. In Zurich it is 2.09. The same error therefore costs roughly three times as much here.
The use case
A married couple, both working, three shared children they can claim, salaries of CHF 174'000 and CHF 157'000. The husband's payslip shows B2 — married single earner with two children. The wife's shows C0: right letter, but no children. Both should have been C3.
Calculated with the official Geneva 2026 tariffs without church tax, assuming twelve equal monthly salaries with no 13th salary and no bonus:
- Husband: 8.60 % instead of 12.62 % — around CHF 6'995 too little a year
- Wife: 16.65 % instead of 11.08 % — around CHF 8'745 too much a year
- Together: around CHF 1'750 too much
Why Geneva bites so hard
Geneva has the highest rate level of the cantons we calculated: with the correct code this household would pay 11.89 % of gross salary. In Zug it would be 4.09 %. Where rates are higher, every error in the code weighs proportionally more — one percentage point off means CHF 1'740 a year at a salary of CHF 174'000.
There is also a Geneva particularity: the canton publishes its tariffs only in the version without church tax. Most other cantons publish two versions, and the last letter of the code decides which applies.
How the Geneva tariff is built
Two structural details explain why the same mistake behaves differently here than in Zurich or Zug. Geneva leaves the first CHF 2'600 of monthly salary out of the tariff altogether, then graduates in steps of CHF 50 up to CHF 19'650 a month and more coarsely above. And the scale keeps rising long past the point where other cantons have flattened: Aargau reaches its ceiling at CHF 95'001 a month and Zurich at CHF 100'001, while Geneva is still climbing well beyond both.
That matters for a wrong tariff letter. In a canton whose scale flattens early, the gap between B and C narrows as the salary grows. In Geneva it does not — so the error keeps close to its full weight across the whole range of salaries most people actually earn.
Geneva is also the only canton in this series that publishes no church-tax version of its tariffs. Elsewhere the last letter of the code picks between two tables. Here there is one, which removes one of the three things that can go wrong — and puts all the weight on the other two.
What these figures are — and what they are not
They concern the running tax-at-source deduction, not the final tax. Because one spouse in this use case already earns more than CHF 120'000, the couple is assessed under the ordinary rules anyway — and the tax at source actually paid is credited there. The wrong code affects the household's liquidity first.
How to check your payslip
The tariff code has three parts: tariff letter, number of children you can claim, church tax marker. Check all three against your actual situation — and on both payslips, not just the conspicuous one.
A correct code is a good first check but not a complete one: with several employments the rate-determining income can be wrong too. In Geneva the third part is fixed — there is no church-tax version — so the letter and the number of children are what to look at. If you find something, report it to HR. For years already closed, a tax-at-source correction should generally be requested by 31 March of the following year. And what you will actually owe in the end only shows once both salaries are calculated together — see our tax advisory for Geneva.
The series: the same error in other cantons
- Zurich — where children relieve the most
- Zug — low rates, large relative deviation
- St. Gallen — both effects strong
- Aargau — the error nobody notices
- Thurgau — when the household pays too little
- Schwyz — the flattest tariffs
- What one child is worth — seven cantons compared