Hour logs on freelancer invoices: What's legally required in Switzerland?

Whether you're a web developer, copywriter, or IT consultant: if you work on an hourly basis, you eventually wonder how detailed your hour logs need to be on the invoice. The short answer: there's no legal requirement to list every hour separately — but there are good reasons to do it anyway, and clear situations where you'll run into trouble without documentation.

What Swiss law actually requires

The Swiss Code of Obligations (CO) and the VAT Act (VATA) do not mandate a detailed hour log on a valid invoice. What must appear on the invoice are the standard mandatory fields for a Swiss invoice: invoice date, unique invoice number, name and address of both parties, service description, amount, and — once you're VAT-registered — tax ID, applicable tax rate, and tax amount.

The service description merely needs to be clear enough that the recipient can assign the invoice to a specific project. "Consulting services March 2026, 18 hours at CHF 150.—" is legally sufficient. The law does not require a line-by-line listing of every work hour.

When hour documentation becomes mandatory anyway

The contract says so

Many clients — especially large corporations, government agencies, and hospitals — explicitly require a timesheet or signed hour record as an invoice attachment in the framework agreement or order confirmation. Check your order confirmation. If it states "proof of services required," accounting will simply reject your invoice without the supporting document, and payment will be delayed.

VAT audits

When the Swiss Federal Tax Administration (FTA) conducts an inspection, it verifies that the services invoiced were actually delivered. If you can't produce documentation, you risk a reassessment. This means: you owe the VAT even if your client has already paid it — plus late-payment interest. A carefully maintained timesheet is your most important protection tool here.

Disputes with the client

If a customer disputes the hours you've invoiced, the burden of proof effectively shifts to you: you must demonstrate that you performed the work. Without documentation, proving your case to a mediator or commercial court becomes difficult. In a dispute, what matters is not what you remember, but what you can document.

What form of hour documentation makes sense?

There's no prescribed format. In practice, three variants have proven effective:

Variant	Effort	Suitable for
Compact line on the invoice	Very low	Regular clients, short projects
Attachment as simple timesheet (PDF)	Low	Projects lasting 1–2 weeks
Project management tool export (e.g. Toggl, Harvest)	Medium	Long-term projects, multiple roles

For most freelancers, a simple timesheet as a PDF attachment suffices: date, activity, hours. You don't need to format this document identically to the invoice — it's a supporting document.

What the invoice itself must contain

Even if you attach the timesheet separately, the invoice itself must contain the essential information. At minimum:

• Type of service: e.g. "Website copywriting and concept development"
• Service period: e.g. "01.07.2026–31.07.2026" (especially important for VAT and correct tax periods)
• Total hours and hourly rate: e.g. "24 hours at CHF 130.—"
• Total amount excl. VAT, VAT amount (8.1%), total amount incl. VAT

For payment via QR-bill, you must also embed the correct QR-IBAN of your account — the step-by-step guide to creating a Swiss QR-bill explains how this works.

Practical workflow: invoice plus timesheet

A clean workflow for freelancers who work on an hourly basis:

1. Record continuously: Log your hours daily or at least weekly — retroactive estimates are worthless in a dispute.
2. Close monthly: At month-end, export the timesheet and verify completeness; have the client sign off if required — an email confirmation is usually sufficient.
3. Create the invoice: Transfer total hours and rate to the invoice. With a tool like the SnapBill app, you can create invoices directly with QR code and all mandatory fields without manually maintaining a template.
4. Send together: Invoice and timesheet as separate PDFs in the same email. Subject line clear: "Invoice No. 2026-047 incl. hour documentation July 2026".
5. Archive: Keep both documents for at least 10 years (legal record retention requirement in Switzerland).

Hourly rate vs. fixed fee: does it make a difference?

With a fixed-price project, the client usually doesn't need an hour log — you've agreed on a flat fee, and whether you invested 30 or 50 hours is not their contractual concern. Still, it's wise to track hours internally: for your own costing, for VAT audits, and for future quotes. Our article Day Rate or Fixed Fee: What Goes on Your Freelancer Invoice covers how daily rates and fixed fees should be correctly shown on the invoice.

At a glance

• Swiss law does not require detailed hour logs on the invoice itself — a clear service description with total hours and rate is sufficient.
• Contractual obligations (framework agreement, order confirmation) may mandate documentation anyway — check before your first invoice.
• During VAT audits by the FTA, a timesheet is your most important supporting evidence.
• In disputes, the service provider effectively bears the burden of proof — without documentation, an hour dispute is hard to win.
• A simple PDF timesheet as an invoice attachment is sufficient in most cases.
• Internal hour tracking pays off even on fixed-price projects — for costing, VAT, and quotes.