Demand before enforcement
Skip the string of polite reminders. After one ordinary reminder, send a formal demand: invoice reference, amount, a clear deadline, and notice that you will start debt enforcement if the deadline passes without payment. That letter is also what puts the debtor formally in default under Art. 102 CO, which is where default interest starts running.
Many debtors treat an open invoice as a free credit line for exactly as long as the creditor's letters stay soft. A demand that names the next step changes the arithmetic.
Use the pause to check your own file. Everything that follows depends on what you can produce: the contract or the order, proof of delivery or performance, the invoice, and any correspondence in which the debtor acknowledged the debt or promised to pay. If the debtor has raised objections to the work itself, deal with them now. A genuine dispute about performance is a different problem from simple unwillingness to pay.
The Betreibung, Switzerland's distinctive first move
Swiss debt enforcement has a feature that surprises foreign creditors. You can set official enforcement in motion without any court judgment: a request to the debt-enforcement office (Art. 67 DEBA) produces a payment summons served on the debtor (Art. 69 DEBA).
It costs little to start, it lands as an official document, and it appears in the debtor's enforcement record, which banks and business partners consult. Against a solvent debtor who was simply stalling, that step alone often produces payment.
Objection, and the road through court
The debtor can stop the whole thing with an objection, the Rechtsvorschlag, and under Art. 75 DEBA does not have to give any reason for it. The roles then reverse. It is on you to have the objection set aside.
This is where your paperwork decides the outcome. With a signed acknowledgement of debt you can ask for provisional dismissal of the objection in summary proceedings (Art. 82 DEBA), which is fast and comparatively cheap. The document does not have to be a single sheet: in BGE 132 III 480 the Federal Supreme Court accepted that an acknowledgement of debt can follow from several documents read together, provided the signed one refers to those that fix the amount.
Without such a document you are in an ordinary lawsuit to establish the claim first (Art. 79 DEBA), with the costs and the timeline that implies. Only once the objection is out of the way can you request continuation of the enforcement under Art. 88 DEBA and reach the debtor's assets. How you papered the deal matters more to collection than anything you do after the invoice goes unpaid.
When it is worth pursuing
Three honest questions before you escalate.
Can the debtor actually pay? Enforcement against an empty shell wins you costs, not cash. Is the claim documented well enough to survive an objection? And does the amount justify the effort, either on its own or as a signal to your other customers about payment discipline?
Sometimes the commercial answer is an instalment agreement with an acknowledgement of debt attached, which hands you the very document that makes any future enforcement quick. If meaningful amounts are outstanding, go through the file with a lawyer before you choose the route.
This is general information, not legal advice. How it applies to your situation depends on the facts, if in doubt, ask.
