Every month, 5% to 15% of your gross salary disappears into “Quellensteuer” or “Imposta alla fonte.” It's the single largest deduction on your Swiss payslip. Yet most frontaliers don't know how it's calculated or that they might be overpaying.
What Is Source Tax?
Source tax is the Swiss income tax for people who don't file an ordinary Swiss tax return. Your employer withholds it directly from your salary each month and sends it to the canton. You don't interact with the Swiss tax authority unless you want to claim deductions (rettifica).
How Your Rate Is Determined
Four factors:
1. Tariff code — the most important factor:
- A = Single (highest rates)
- B = Married, spouse doesn't work (significantly lower)
- C = Married, dual income
- H = Single parent
- Number = dependent children (more children = lower rate)
2. Salary level — progressive curve (no sudden bracket jumps like IRPEF).
3. Canton — each publishes own tables. Ticino is medium-tax.
4. Church membership — adds 1-2% if registered with a Swiss church. Most frontaliers aren't.
What the Rates Actually Look Like
Tariff A0 (Single, no children) — Ticino 2026:
| Gross Annual | Rate | Monthly on CHF 5K |
|---|---|---|
| CHF 40,000 | ~6.5% | CHF 217 |
| CHF 60,000 | ~10.0% | CHF 500 |
| CHF 80,000 | ~12.5% | CHF 833 |
| CHF 100,000 | ~14.0% | CHF 1,167 |
Tariff B1 (Married, 1 child, single income):
| Gross Annual | Rate | Monthly on CHF 5K |
|---|---|---|
| CHF 40,000 | ~2.0% | CHF 67 |
| CHF 60,000 | ~5.5% | CHF 275 |
| CHF 80,000 | ~8.5% | CHF 567 |
| CHF 100,000 | ~10.5% | CHF 875 |
The difference is dramatic. CHF 70,000 salary: A0 pays CHF 671/month vs B1 pays CHF 408/month. That's CHF 3,156/year — just from the tariff code.
Old Agreement vs New Agreement
Old (pre-July 2023): Switzerland retains 100%. Italy does NOT tax (IRPEF exempt). Source tax is your ONLY income tax.
New (post-July 2023): Switzerland applies 80% rate. Returns 40% to Italy (ristorno). Italy taxes with IRPEF but gives credit for Swiss tax. €10,000 franchigia if within 20km. Total tax = Swiss + Italian IRPEF - credit.
The Year-End Correction (Conguaglio)
Every December, your employer recalculates for the full year. Adjusts for salary changes, tariff changes, 13th month. Overpaid = refund. Underpaid = extra deduction. Normal, not an error.
How to Pay Less (Legally)
1. Correct your tariff. The easiest fix. Email HR within 14 days of any life change (marriage, child, spouse working status).
2. File the rettifica (by March 31). Claim deductions: pillar 3a (CHF 7,056), LPP buy-in, commuting costs, alimony, child care. Typical savings: CHF 500-2,000/year. A commercialista handles it for CHF 200-400.
3. Contribute to pillar 3a and/or LPP buy-in. The deductions need actual contributions behind them. Both require the rettifica to claim the benefit.
Five Things to Check on Your Next Payslip
1. Tariff code matches your situation? 2. Gross salary base correct? 3. Church tax applied when it shouldn't be? 4. Effective rate matches the tables? 5. December conguaglio — large refund means you overpaid all year.
Last updated: June 2026. Rates are approximate for Canton Ticino. Official tables published by Divisione delle contribuzioni. This does not constitute tax advice.
blog.authorBio