Calculators tell you the amount. This list tells you what to do and by which date, with an official source for every fact. Each entry shows when it was last re-checked against that source.
The badge on each card shows how long ago the fact was re-checked against its official source.
Request the tax return (NOV) by 31 March or lose your deductions
All cantonsmoney lost if missed
Who
Residents on permit B or L taxed at source (Quellensteuer) who want to claim pillar 3a, commuting costs, pension buy-ins or other deductions.
What to do
File the request for subsequent ordinary assessment (NOV) with your cantonal tax office, electronically where offered. Once filed it cannot be withdrawn, and NOV then applies every following year, so run the numbers first (see the savings check).
Deadline
31 March of the year after the tax year. Hard deadline: no extension, late requests are not processed.
Gross income 120'000+ makes the full tax return mandatory, forever
All cantonsmoney lost if missed
Who
Source-taxed residents whose gross yearly salary reaches CHF 120'000, or married couples where one spouse reaches it.
What to do
Expect a mandatory ordinary assessment covering your worldwide income and wealth. It stays mandatory in every later year even if income drops below the threshold. Keep records of foreign accounts and assets: they become declarable.
Deadline
Triggered automatically in the year the threshold is reached; the tax office sends the return forms.
Leaving Switzerland? File the NOV request before you deregister
All cantonsmoney lost if missed
Who
Source-taxed residents moving abroad who still want to claim deductions for their final year.
What to do
Submit the NOV request no later than the date you deregister with your municipality (Abmeldung). After departure the 31 March deadline no longer protects you: the earlier date wins.
Permit C or marrying a C-permit holder / Swiss ends source tax the next month
All cantonsgood to know
Who
Source-taxed employees who receive permit C, Swiss citizenship, or marry someone holding either.
What to do
From the following month nothing is withheld from your salary, but the full year is settled later through an ordinary tax return with provisional installments. Set the former withholding amount aside monthly or the first bill will hurt. After divorce or separation the switch reverses.
Deadline
Automatic from the month after the event; report the change to your employer and tax office promptly.
Pillar 3a counts only if credited by 31 December (2026 max: 7'258)
All cantonsmoney lost if missed
Who
Anyone with earned income paying into pillar 3a. 2026 maximum: CHF 7'258 with a pension fund, CHF 36'288 (20% of income) without one.
What to do
What matters is the date the money is booked on the 3a account, not the day you send it. Transfers around New Year can land in January and shift the deduction to the next tax year. Pay by mid-December.
Deadline
31 December, by value date on the 3a account. Practical safe deadline: around 15 December.
Since 2026 you can buy back missed pillar 3a years
All cantonsgood to know
Who
People who skipped or underpaid pillar 3a in 2025 or later and had AHV-liable earned income in that gap year.
What to do
On top of the regular yearly maximum you may pay in one extra annual amount (CHF 7'258 in 2026) per year to close gaps from 2025 onwards. The buy-in is deductible like a normal contribution. Gaps older than 2025 cannot be bought back.
Deadline
Gaps stay purchasable for 10 years after the gap year.
Wrong confession on file means paying church tax you do not owe
All cantonsgood to know
Who
Source-taxed employees. In most cantons the source-tax tariff comes in variants with and without church tax, chosen from the confession your employer has on file.
What to do
Check the tariff code on your payslip (the letter Y/N after the tariff usually marks church tax). If you are not a member of a recognised church, tell HR to correct the confession; overpaid months can be reclaimed via tariff correction or NOV.
Deadline
Tariff correction request: 31 March of the following year in most cantons.
You have 30 days to object to the assessment. Then it is locked
All cantonsmoney lost if missed
Who
Anyone receiving a final assessment (definitive Veranlagung / Einschaetzungsentscheid), including after an NOV and after a discretionary assessment.
What to do
Check the decision against your declaration the day it arrives. If anything is wrong, send a written, signed Einsprache with reasons and documents by registered mail within the window. It is free. Not sure the letter is an assessment? Use the letter decoder.
Deadline
30 days from the day after delivery. A forfeiture deadline: no extension; restoration only for narrow cases like serious illness. Authorities are not obliged to fix errors afterwards.
Ordinarily assessed residents moving between cantons. (Source-taxed employees instead switch tariff from the month after the move.)
What to do
When moving between cantons, the canton and municipality of residence on 31 December collect the ordinary tax for the entire year. Moving in December into a cheaper municipality applies its rates to all 12 months; the reverse is also true, so time the move consciously (exceptions: NW/OW use 1 January, Fribourg splits pro rata). Price your specific move on the Moving page.
Deadline
31 December: the registered residence on that date decides.
This is general information, not tax advice. Rules differ by canton and personal situation; always confirm with the linked official source or your cantonal tax office.