
Tax advisory for engineering firms in Diegten: what every SME should know
Tax advisory for engineering firms in Diegten 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.
The Swiss legal frame for tax advisory
Responsibility for the books is personal: in an SA, organising the accounting is one of the board's non-transferable duties (art. 716a CO); in a Sàrl, the managing directors carry the same duty. Outsourcing the execution never transfers that underlying responsibility, including for a company based in Diegten.
Art. 957a CO requires complete, truthful and systematic recording of transactions, each entry backed by a supporting document. For tax advisory, that means in practice: no movement without a receipt, and an audit trail that can be reconstructed at any time — including during a VAT or AHV inspection.
Year-end closing: how the mechanics work
Accrual accounting is the technical heart of the closing: every income and every expense belongs to the year it economically concerns, regardless of the payment date. Rents paid in advance, insurance premiums straddling the date, supplier invoices arriving in January: all flow through accrual accounts.
For tax advisory, a closing checklist reused every year transforms the exercise: same steps, same checks, same documents — only the year changes.
A Swiss SME's accounting calendar
Extensions exist and can be requested: cantonal deadlines for the tax return, deferral of the VAT filing on a reasoned request. But an extension does not stop interest: on VAT, default interest runs from the ordinary due date even when more time has been granted.
For tax advisory, year-end is prepared in October: last invoices, investment decisions, provisions to assess — December is too late to act, January is for recording.

Swiss VAT: rates, threshold and filings
Since 1 January 2024, Swiss VAT rates are 8.1% (standard), 2.6% (reduced — food, books, medicines) and 3.8% (accommodation). Registration becomes mandatory from CHF 100,000 of worldwide annual turnover. For tax advisory, step one is therefore checking the threshold and choosing the right reporting method.
Also useful for tax advisory: some supplies are excluded from VAT (health, education, property rental) — with no corresponding input VAT right. Qualifying revenues correctly from the start avoids surprises.
Diegten: what changes, what does not
Diegten (postal code 4457, canton Basel-Country) applies the same federal rules as the rest of the country: what changes in Diegten are the cantonal counterparts — tax administration, compensation office, commercial register.
For a business in Diegten, that means VAT returns identical to anywhere in Switzerland, but a tax return and family allowances governed by the canton Basel-Country.
Frequently asked questions
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 Diegten as anywhere.
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 Diegten as everywhere in Switzerland.
Effective VAT method or net tax rate: how to choose?
The effective method deducts actual input VAT and files quarterly; the net tax rate method applies a flat industry rate to turnover, semi-annually, with no separate input VAT deduction. The flat rate suits low-cost structures; as investments grow, the effective method usually wins again. The choice rests on the company's own figures, in Diegten as anywhere.
How long must records related to tax advisory be kept?
Ten years from the end of the financial year concerned (art. 958f CO). Electronic retention is permitted if the integrity and readability of the records are guaranteed — a serious digital archive validly replaces paper binders. A business in Diegten can therefore archive fully digitally.
Also worth reading
In neighbouring municipalities
Switch to accounting that keeps itself up to date
MyFiducia.ai automates tax advisory for businesses in Diegten: 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.