
E-invoicing for engineering firms in Trélex: rules, deadlines, best practice
E-invoicing 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.
Digitalising e-invoicing: what actually works
Artificial intelligence has changed the economics of e-invoicing: automatic invoice reading reaches recognition rates that make manual entry marginal, and posting suggestions learn from corrections. The accountant does not disappear — the job shifts from data entry to control and advice.
For e-invoicing, migrating history must not block the start: begin on day one of the current financial year and import the history later if needed.
A well-structured SME chart of accounts
A chart of accounts gets documented: one description line per account (what, when, VAT) is enough for two people to post the same way. It is the quality manual of e-invoicing, valid in Trélex as anywhere.
For e-invoicing, the right granularity is decisive: enough accounts to steer the business (margins by activity, expenses by nature), few enough that every entry finds its place without hesitation. The VAT accounts (input VAT, VAT due) deserve special care — they are the basis of the annual reconciliation.
Outsource e-invoicing or keep it in-house?
A fiduciary's cost depends first on the quality of the data received: digitised, filed, reconciled documents are processed fast; a box of loose receipts is billed by the hour. Improving the internal preparation of e-invoicing lowers fees more surely than any negotiation.
A business in Trélex can combine the models: internal day-to-day entry, monthly external supervision, closing and taxes with the specialist — e-invoicing splits very well.

The Swiss legal frame for e-invoicing
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.
For e-invoicing, the classic early mistake remains mixing private and business: a dedicated bank account and documented private withdrawals eliminate half the discussions with the tax office.
Trélex: what changes, what does not
Working with a fiduciary from Trélex no longer depends on geography: the documents of a business in Trélex are shared online, while the canton Vaud keeps its own deadlines for the tax return.
Federal deadlines do not move in Trélex: VAT within 60 days, salary declaration in January, 10-year record retention — postal code 1270 changes nothing about those rules, only the sender's address.
Frequently asked questions
Can e-invoicing be automated with AI?
Largely, yes: automatic document reading, posting suggestions, bank reconciliation via QR references and VAT exports. Human approval remains essential — AI prepares, the professional checks. That is exactly how MyFiducia.ai approaches e-invoicing.
What is the difference between a limited and an ordinary audit?
The ordinary audit applies to companies exceeding, for two consecutive years, two of three thresholds: CHF 20 million balance sheet total, CHF 40 million revenue, 250 full-time positions. Others fall under the limited audit, and those with no more than ten full-time positions on annual average can opt out with all shareholders' consent. These federal thresholds do not depend on the registered seat — in Trélex as anywhere.
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.
Which documents should be prepared for the year-end closing?
Bank and cash statements at the closing date, the inventory of stock and work in progress, final AHV/LPP/accident settlements, contracts signed or amended during the year, invoices straddling two years and the detail of accruals. With an up-to-date document archive, most of it is already there. The list is identical in Trélex: the CO dictates it, not the commune.
Also worth reading
In neighbouring municipalities
Switch to accounting that keeps itself up to date
MyFiducia.ai automates e-invoicing 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.