Tax Declaration for Self-Employed: Complete Guide 2025
As a self-employed person in Switzerland, your tax return is more complex than that of a salaried employee. You must declare your business income, but also manage your provisional installments, maximize your deductions and anticipate your tax burden. This guide details each step to fill out your declaration correctly and pay the right amount of taxes.
Income to Declare
Self-Employment Income
The taxable income from your business is calculated as follows:
- Total turnover: all invoices issued during the fiscal year (collected or not, depending on the accounting method)
- Less: deductible expenses: all justified professional expenses
- = Net self-employment income
Important: if you operate as a sole proprietorship, this net income is directly added to your other personal income for the tax calculation. In an LLC, it is the salary you pay yourself that is taxed (plus corporate profit tax).
Other Income to Declare
- Salaries (if mixed salaried + self-employed activity)
- Investment income: bank interest, dividends, capital gains
- Real estate income: rental income, imputed rental value of housing
- Pensions and annuities: OASI, occupational pension (LPP), pillar 3a (upon withdrawal)
Deductible Expenses: Exhaustive List
Direct Professional Expenses
| Category | Examples | Condition |
|---|---|---|
| Office | Rent, electricity, internet, furniture | Professional portion only |
| Equipment | Computer, printer, software (ToBill) | Depreciation if > CHF 1,000 |
| Vehicle | Fuel, insurance, maintenance, depreciation | Professional share |
| Travel | Train, plane, parking, taxi | Business trips only |
| Training | Courses, seminars, conferences | Related to current activity |
| Insurance | Professional liability, legal protection | Professional premiums |
| Professional fees | Fiduciary, lawyer, notary | Supporting invoices |
| Marketing | Website, advertising, business cards | Fully deductible |
| Telecom | Phone, mobile internet | Professional portion (50-80%) |
| Bank fees | Account maintenance, transfers | Professional account |
Home Office
Deductible only if a room is exclusively dedicated to professional activity and you do not have an external office.
Calculation: pro rata based on surface area.
- Apartment 80 m², office 12 m² = 15%
- Annual rent CHF 24,000 --> deduction: CHF 3,600
- Charges (electricity, internet, heating) at the same pro rata
Deductible Social Contributions
- OASI/DI/APG: approximately 10.1% of net income (calculated by the compensation office)
- Pillar 3a: up to CHF 7,056 (with LPP) or CHF 35,280 (without LPP, capped at 20% of net income) in 2025
- LPP buybacks: fully deductible if you are affiliated with a pension fund
- Family allowances: employer contributions are deductible
Depreciation
Professional assets worth more than CHF 1,000 must be depreciated over their useful life:
| Asset Type | Annual Depreciation Rate |
|---|---|
| Office furniture | 20-25% |
| Computer equipment | 30-40% |
| Vehicle | 30-40% |
| Machinery and tools | 20-30% |
| Interior fittings | 10-20% |
Example: a computer purchased for CHF 3,000 with a depreciation rate of 40% allows you to deduct CHF 1,200 in the first year, CHF 720 in the second, etc.
Tax Calculation: DFT and SCT
Direct Federal Tax (DFT)
The DFT applies to your net income after deductions, with a progressive scale:
| Taxable Income | Marginal DFT Rate |
|---|---|
| Up to CHF 31,600 | 0% |
| CHF 31,600 - 41,400 | 0.77% |
| CHF 41,400 - 55,200 | 0.88 - 2.64% |
| CHF 55,200 - 72,500 | 2.97% |
| CHF 72,500 - 78,100 | 5.94% |
| CHF 78,100 - 103,600 | 6.60% |
| CHF 103,600 - 134,600 | 8.80% |
| CHF 134,600 - 176,000 | 11.00% |
| Over CHF 176,000 | 11.50% |
Scale for single persons. Different scale for married couples.
State and Municipal Tax (SCT)
The SCT varies considerably depending on the canton and municipality. Here is an estimate for a net income of CHF 100,000 (single person):
| Canton | Estimated SCT | Total Burden (DFT + SCT) |
|---|---|---|
| Zug | ~CHF 10,000 | ~CHF 16,000 |
| Schwyz | ~CHF 11,500 | ~CHF 17,500 |
| Nidwalden | ~CHF 12,000 | ~CHF 18,000 |
| Zurich | ~CHF 16,000 | ~CHF 22,000 |
| Bern | ~CHF 19,000 | ~CHF 25,000 |
| Vaud | ~CHF 22,000 | ~CHF 28,000 |
| Geneva | ~CHF 25,000 | ~CHF 31,000 |
Complete Example
Profile: self-employed sole proprietor, Canton of Vaud, Lausanne, single.
| Item | Amount |
|---|---|
| Turnover | CHF 150,000 |
| Professional expenses | -CHF 30,000 |
| OASI/DI/APG contributions | -CHF 12,000 |
| Pillar 3a | -CHF 7,056 |
| Taxable income | CHF 100,944 |
| DFT | ~CHF 5,800 |
| SCT (VD, Lausanne) | ~CHF 22,000 |
| Total taxes | ~CHF 27,800 |
Effective tax rate: 27.5% of taxable income.
Provisional Installments
How It Works
The tax administration sends you provisional installment notices based on your last declaration. You generally pay in 10 monthly installments (or quarterly depending on the canton).
Modifying Installments
If your income changes significantly, you can request a modification of the installments:
- Income increase: increase your installments to avoid a large catch-up payment (with default interest)
- Income decrease: request a reduction to preserve your cash flow
Interest:
- Default interest (late payment): 4 to 5% depending on the canton
- Compensatory interest (overpayment): 0 to 1% depending on the canton
Recommended Provisioning
Set aside 25 to 30% of each cash receipt for taxes and social contributions. ToBill helps you track your results in real time and estimate your tax burden.
Filing Deadlines by Canton
| Canton | Standard Deadline | Extension Possible |
|---|---|---|
| Geneva (GE) | March 31 | Until September 30 (upon request) |
| Vaud (VD) | February 28 | Until September 30 (if fiduciary) |
| Zurich (ZH) | March 31 | Until September 30 (upon request) |
| Bern (BE) | March 15 | Until September 15 (upon request) |
| Fribourg (FR) | March 31 | Until September 30 (upon request) |
| Valais (VS) | March 31 | Until November 30 (upon request) |
| Neuchatel (NE) | February 28 | Until June 30 (upon request) |
| Jura (JU) | March 31 | Until September 30 (upon request) |
Late penalties:
- First reminder: free to CHF 50
- Second reminder: CHF 50 to 150
- Ex officio assessment: if no declaration is filed, the tax authority estimates your income (often unfavorably)
Legal Tax Optimization Strategies
1. Maximize Pillar 3a
Pillar 3a is the most powerful tax lever for self-employed individuals:
- With LPP: contribute the maximum of CHF 7,056
- Without LPP: contribute up to CHF 35,280 (20% of net income)
- Savings: at a marginal rate of 35%, contributing CHF 7,000 = CHF 2,450 in tax savings
Tip: open multiple 3a accounts (max 5) to optimize staggered withdrawals at retirement.
2. Plan Your Investments Ahead
Make your professional purchases (equipment, software, training) before December 31 to deduct them from the current fiscal year.
Example: purchasing a computer for CHF 2,500 in December. If your marginal rate is 35%, you save CHF 875 in taxes one year earlier.
3. Smooth Your Income
The progressive scale penalizes exceptional years. If possible:
- Spread the invoicing of large projects over two fiscal years
- Postpone certain services if your turnover is already high
- Anticipate expenses at year-end
4. LPP Buybacks (if LLC)
If you are affiliated with a pension fund, LPP buybacks are fully deductible. This is particularly effective for high incomes.
5. Choose the Right Canton
The difference in tax burden can reach 20% of income between the most and least expensive cantons. If you are considering a move, run a comparative simulation.
6. Switch to LLC if Relevant
From approximately CHF 150,000 in net income, LLC taxation can become more advantageous thanks to the salary/dividend split. Consult your fiduciary for a personalized simulation.
Documents to Prepare for Your Declaration
Mandatory
- Income statement: summary of income and expenses for the fiscal year
- Balance sheet (if double-entry bookkeeping): statement of assets and liabilities as of December 31
- OASI certificate: amount of contributions paid
- Pillar 3a certificate: amount contributed during the year
- Bank statements: all professional and personal accounts
- LPP certificate: pension assets and buybacks made
Supporting Documents to Keep (10 years)
- All invoices issued and received
- Payment receipts
- Contracts and purchase orders
- Expense reports with supporting documents
- Vehicle logbook (if claiming mileage deduction)
Prepare Your Declaration with ToBill
Automated Export
ToBill automatically generates the documents needed for your declaration:
- Annual turnover: all invoices issued, sorted by month
- Expenses by category: expenses classified according to the SME chart of accounts
- VAT summary: VAT collected and deductible by quarter
- PDF supporting documents: all accounting documents stored and accessible
- Fiduciary export: compatible format CSV, Excel, API
Real-Time Estimation
- Track your monthly and cumulative results
- Anticipate your tax burden with the built-in estimator
- Provision intelligently with automatic alerts
Result: complete your tax return in 30 minutes instead of 3 hours, with the certainty of not missing any deduction.