
Sàrl incorporation for engineering firms in Trélex explained simply
Sàrl incorporation for engineering firms in Trélex rests on three pillars: federal law that applies across Switzerland, cantonal deadlines worth knowing, and tools that eliminate re-keying. This guide puts it all in order, fact by fact.
Choosing the structure: Sàrl, SA or sole proprietorship
Contributions in kind (vehicle, equipment, client portfolio) are possible when founding a Sàrl or an SA, but they follow strict valuation and disclosure rules. Cash contribution remains the simple route, in Trélex as elsewhere.
First accounting reflex for Sàrl incorporation: open the document numbering with the very first expense, even before registration. Founding costs are deductible — if documented.
Digitalising Sàrl incorporation: what actually works
Security is part of digitalisation: named access, tested backups, encryption of sensitive data. A digital accounting file is protected like a safe — because it is one.
For Sàrl incorporation, migrating history must not block the start: begin on day one of the current financial year and import the history later if needed.
The Swiss legal frame for Sàrl incorporation
AHV audits and VAT audits follow the same logic: start from the documents, trace to the entries, check consistency. A business in Trélex with a clean audit trail sails through these exercises.
Late books show from the outside: poorly calibrated tax instalments, provisional filings, slow answers to the bank. Staying current is also a matter of image.

Swiss VAT: rates, threshold and filings
Charging VAT is not a matter of style: the number, the correct rate, the tax amount — the tax administration checks the form as closely as the substance, including at SMEs in Trélex.
Input VAT deduction is the flip side of VAT charged: tax paid on purchases and investments comes back through the return, receipt in hand. Rigorous entry of supplier invoices therefore translates directly into cash.
Trélex: what changes, what does not
Sole proprietorship, Sàrl or SA in Trélex: the AHV contact remains the competent compensation office, and taxes follow the scales of the canton Vaud.
Trélex requires no special bookkeeping: the Code of Obligations applies at postal code 1270 as everywhere else, and a well-kept digital file transfers smoothly to any auditor in the canton.
Frequently asked questions
When is entry in the commercial register mandatory?
A Sàrl and an SA only come into existence with their registration. A sole proprietorship must register from CHF 100,000 of annual revenue; below that, registration stays voluntary but adds credibility and protects the business name. Registration goes through the canton's commercial register office — for Trélex too.
What are the legal obligations for Sàrl incorporation in Switzerland?
The foundation is the Code of Obligations: proper bookkeeping (art. 957a CO), annual accounts (balance sheet, income statement, notes) and 10-year retention of books and records (art. 958f CO). VAT applies from CHF 100,000 of turnover, and social insurance settlements from the first employee. Nothing is different in Trélex: federal law applies.
What is simplified bookkeeping and who can use it?
Sole proprietorships and partnerships under CHF 500,000 of revenue may limit themselves to recording income, expenses and assets (art. 957 para. 2 CO). Once over the threshold — or upon founding a Sàrl or an SA — full accounts with balance sheet, income statement and notes become mandatory. The CHF 500,000 threshold is assessed the same way in Trélex.
When must a business register for VAT?
As soon as its worldwide annual turnover reaches CHF 100,000 (CHF 250,000 for non-profit sports or cultural associations). Below that, voluntary registration remains possible and often makes sense to reclaim input VAT on investments. The threshold is federal: it applies in Trélex as everywhere in Switzerland.
Also worth reading
In neighbouring municipalities
Switch to accounting that keeps itself up to date
MyFiducia.ai automates Sàrl incorporation for businesses in Trélex: AI-read documents, posting suggestions, VAT and exports ready for your fiduciary. Try the platform or browse our other guides.
The application is operated in French.