The biggest single figure in the tariff code
Every payslip with tax at source carries a code with three parts: the tariff letter, the number of children you can claim, and a marker for church tax. C3N therefore means: dual earner, three children, no church tax.
Of those three, the number of children is the most powerful — and the one that changes most often. A birth has to be reported and then processed in payroll. If either step is missed, the deduction runs on with the old figure for years.
What a missing child costs
Calculated at a salary of CHF 157'000, tariff C, using the official 2026 tariffs without church tax and twelve equal monthly salaries. The amounts show by how much the annual deduction falls when one more child you can claim is added:
| Canton | 1st child | 2nd child | 3rd child | three children total |
|---|---|---|---|---|
| Zurich | 3'061 | 3'030 | 2'763 | 8'854 |
| Geneva | 3'030 | 2'905 | 2'810 | 8'745 |
| St. Gallen | 2'402 | 2'324 | 2'229 | 6'955 |
| Zug | 2'025 | 1'884 | 1'570 | 5'479 |
| Aargau | 1'884 | 1'884 | 1'570 | 5'338 |
| Thurgau | 1'633 | 1'507 | 1'397 | 4'537 |
| Schwyz | 1'303 | 1'240 | 1'146 | 3'689 |
The difference between Zurich and Schwyz is more than double for the first child — at exactly the same salary. If you are weighing up a move between cantons, this is a figure that rarely appears in comparisons.
Each additional child relieves a little less
In all seven cantons the effect tapers slightly with each additional child. In Zurich the first child brings CHF 3'061, the third still CHF 2'763. Geneva is the most even, with only CHF 220 between the first and third child. Zug tapers most: from CHF 2'025 down to CHF 1'570.
Why the third child is often the trigger
Our canton series follows a married couple with two entries wrong in the payroll system. The third child plays a key role there: run the same situation with only two children and the result reverses in six of the seven cantons.
The reason is simple: the more children missing from the tariff, the larger the deviation. With one missing child it often stays unremarkable; with three it does not.
Two cut-off dates worth keeping apart
For the tariff code, a child generally counts from the month after the birth. For the tax return, the situation on 31 December decides, and the deduction is then granted for the whole year.
A child born in November therefore affects the salary deduction for two months only — but the later assessment for the full year. That is not a contradiction, just the consequence of two different systems.
What these amounts are — and what they are not
All the figures here concern the running tax-at-source deduction, meaning what leaves your salary each month. They say nothing about how the final tax turns out. If an ordinary assessment follows — mandatory above CHF 120'000 gross salary, and for married couples it is enough for one of you to cross the threshold — the tax at source already paid is credited against the final tax, and the child deductions follow the ordinary rules there.
What you can do
Check the tariff code on the payslip after every birth — on both spouses' payslips. If the number is wrong, report it to HR. For years already closed, a tax-at-source correction should generally be requested by 31 March of the following year.