Almost every Swiss invoice carries a number in the format CHE-123.456.789 MWST. Most people skip over it. Yet this number decides whether the VAT shown can be deducted as input tax. A supplier who charges VAT without being in the register costs you exactly that amount at the next audit.
This article explains what the UID is, how to read it, and where to check in one minute whether a supplier is VAT-registered.
What the UID is and how it is built
The Enterprise Identification Number (UID, from the German Unternehmens-Identifikationsnummer; IDE in French, IDI in Italian) is the single identifier for every business in Switzerland. It is issued by the Federal Statistical Office (FSO) and kept in the public UID register. Structure:
- CHE as the country prefix,
- nine digits in three groups of three, for example 123.456.789,
- the last digit is a check digit. Typing errors and invented numbers are therefore usually caught on form alone.
According to the FTA, the VAT number is the same UID with the suffix "MWST": CHE-123.456.789 MWST. The suffix may also be in French (TVA) or Italian (IVA); "VAT" is not permitted. Other spellings such as CHE123456789MWST or "VAT no.: 123.456.789" occur and do not prevent the deduction, provided the other conditions of Art. 28 ff. of the VAT Act are met.
Important: every business has a UID, including businesses that are not VAT-registered. The "MWST" suffix on its own proves nothing. What counts is whether the VAT status in the register is active.
Why the supplier's VAT registration is your problem
Under Art. 28 para. 1 let. a of the VAT Act, you may deduct the domestic tax invoiced to you. Art. 26 para. 2 of the VAT Act requires the invoice to show the supplier's name, a note that the supplier is registered as a taxable person, and the registration number.
If someone charges VAT without being registered, they owe the tax shown to the Confederation (Art. 27 para. 2 VAT Act). For you as recipient, that does not mean the deduction goes through: in an audit, the FTA checks whether the supplier was in the register at the time of supply. If not, the input tax is added back, up to five years retroactively (Art. 42 para. 1 VAT Act), with default interest (4 % since 2026, Federal Department of Finance).
In practice: an invoice for CHF 1,000 net plus CHF 81 VAT from an unregistered supplier costs you CHF 1,081, and the CHF 81 does not come back.
Typical cases in practice
- Small business below the threshold. Below CHF 100,000 annual turnover, a business is exempt from VAT liability and must not show VAT; some do out of habit or because the invoice template includes it.
- Newly founded company. The UID exists, VAT registration has been applied for but is not yet active.
- Deregistered company. The business was liquidated or its VAT liability ended; the invoice template stayed.
- Wrong number. Transposed digits, the number of another company in the same group, or the number of a sole proprietorship while the invoice comes from a GmbH.
- Invoice with no number at all, but with VAT shown.
Checking a supplier in the UID register
The check is free and needs no login:
- Open uid.admin.ch.
- Enter the UID or the company name.
- In the entry, look at the VAT section: status (active / inactive), start and, if applicable, end of VAT liability.
- Compare name and registered office with the invoice. The legal form must match (AG, GmbH, sole proprietorship).
Do not check only new suppliers. VAT liability can end without the invoices changing.
Checklist: UID and VAT number
- Number present, format CHE-xxx.xxx.xxx with suffix MWST/TVA/IVA?
- Check digit formally correct?
- Entry found on uid.admin.ch, name and legal form match?
- VAT status active on the date of supply?
- Rate and amount shown plausible (see Checking VAT rates)?
- If in doubt: do not deduct input tax, ask the supplier for a corrected invoice.
Automatic UID check on every invoice
Klyrenta reads the VAT number from every uploaded invoice, checks format and check digit, and matches it against the federal UID register. If the supplier is not registered as a taxable person, an error appears with the amount that would not be deductible. If the number is missing entirely, that is reported. Added to this are duplicate detection, rate and amount checks, and the IBAN comparison with earlier invoices.
Klyrenta does not decide on the input tax deduction and files nothing with the FTA; it shows where to look. Data stays in Switzerland at Infomaniak; files are deleted after 90 days.
10 invoices free, then from CHF 49 one-time for 100. Fiduciaries can use the receipt inbox for several clients from CHF 149 per month. More: Invoice review for SMEs.
Checked against the official sources named in the text.