Digital Signatures on Invoices (digitale Signatur): When a Swiss Business Actually Needs One

Your invoice is ready and the client asks: will it be signed? For most Swiss businesses the honest answer is no — and legally so: no Swiss statute demands a signature on an invoice. A plain PDF is a valid Rechnung. Yet in specific situations they matter.

What Swiss law actually requires on an invoice

The VAT Act stays dry: Art. 26 MWSTG demands that an invoice clearly identify supplier, recipient and nature of the supply and, as a rule, carry the listed elements — names and locations, the taxable-person note with your register number, the date, the supply, the consideration, and the tax rate with the tax amount.[2] A signature appears nowhere in that list.

Civil law adds nothing stricter: where no form is prescribed, any form will do — an invoice is not a formal deed. An unsigned PDF carries your payment claim as well as a signed letter.

The signature line many templates carry is a paper-era courtesy. VAT problems come from missing or wrong mandatory data — a missing UID, no tax rate — never from a missing signature.

So the standard Swiss invoice is an unsigned PDF, often archived as PDF/A, with a QR-bill for payment. Nothing in that workflow needs a certificate.

The signature ladder defined by ZertES

The Federal Act on Electronic Signatures (ZertES) regulates certification services — certificate quality, provider recognition, rights and duties — not signature practice itself.[3]

It defines a ladder: a simple electronic signature is data attached to a document to authenticate it; an advanced one must be uniquely linked to its holder, identify them, be created under their sole control, and make later changes detectable. A regulated signature adds a secure signature-creation device and a valid regulated certificate; the qualified signature (QES) is a regulated signature based on a qualified certificate.[3]

The rung with legal teeth sits in the Code of Obligations: under Art. 14(2bis) OR, a QES is equal to a handwritten signature and satisfies a statutory written-form requirement unless the law provides otherwise.[4]

You cannot make one yourself: a pasted scan of your handwriting or a PDF tool’s sign button creates at best a simple signature — visually convincing, legally weightless. Qualified certificates come only from recognised providers: today DigiCert Switzerland, SIGN8, Swisscom, SwissSign and the federal BIT, reserved for the administration.[1]

When signing genuinely matters

Written form is the first case: a QES counts as handwriting wherever the law demands it — a suretyship, certain notices, some contracts. An ordinary invoice almost never carries such a duty.

EU clients are the second. EU VAT law requires the authenticity of the origin, the integrity and the legibility of an invoice to be ensured, but leaves the business free to choose how — an advanced electronic signature with a qualified certificate and a secure creation device, and EDI, are the named examples.[5]

Recognition is the catch: Switzerland has no mutual-recognition agreement with the EU, so a Swiss QES is not automatically treated as its EU counterpart — negotiations were mandated only in January 2025.[1]

The last case is disputes: a verifiable signature strengthens your position when a client denies an invoice or fraudsters send fakes in your name. For most SMEs that day never comes — so unsigned remains the Swiss default.

A sane workflow for Swiss invoices

Default to plain PDF plus QR-bill: the QR-IBAN and reference route and reconcile the payment automatically, so verification happens in the payment flow, not on the document.

When a client asks for a signed invoice, ask what they mean. A visible signature satisfies them psychologically; legally, only a QES equals handwriting — and no Swiss invoice needs even that.[4]

If a tender or foreign contract genuinely requires signatures, use a signing service from the recognised providers’ list and let recipients verify documents through the federal validator at validator.admin.ch.[1]

Then automate the rest: facturio keeps every mandatory field complete, attaches compliant QR-bills and archives each document — signed where it matters, unsigned elsewhere. Sources: [1] BAKOM, Elektronische Signatur; [2] Federal VAT Act (fedlex); [3] ZertES (fedlex); [4] EasyGov, QES; [5] EUR-Lex, Council Directive 2006/112/EC.