IBAN format · CH
Swiss IBAN format
The Swiss IBAN format is defined by ISO 13616 and is fixed for every account opened in Switzerland. A Swiss IBAN is always 21 characters long and uses the structure pattern 5!n12!c: 5 digits (0–9), then 12 characters (A–Z, 0–9). The first two characters are the country code CH, the next two are MOD 97 check digits, and the remaining 17 characters form the BBAN, which Switzerland divides into 2 fields. This page breaks down each field, shows a worked CH IBAN, and explains how the check digits are computed.
Structure breakdown
The Switzerland BBAN (positions 5–21) is the country-specific part of the IBAN and is 17 characters long. Switzerland splits it into 2 fields: Field 1 is 5 digits; Field 2 is 12 characters. The exact meaning of each field (bank code, branch, account number) is defined by Switzerland's national registry and is stable, so a CH IBAN that matches the pattern and length is structurally valid even before the MOD 97 check.
The table below applies the 5!n12!c pattern to a real, MOD 97-valid Switzerland IBAN (CH9300762011623852957). Each row shows one field of the IBAN — country code, check digits, then the BBAN fields in order — so you can see exactly how a CH IBAN is assembled. This is the same breakdown the IBAN validator produces when you paste a Switzerland IBAN.
Swiss IBAN check digits
Positions 3–4 of a Switzerland IBAN hold two MOD 97-10 check digits. ISO 13616 computes them by rearranging the IBAN so the BBAN leads and the country code plus check digits trail, converting letters to numbers (A=10 … Z=35), and taking the giant resulting integer mod 97. The check digits are chosen so the whole IBAN leaves a remainder of 1. If any single character of a CH IBAN is mistyped, the remainder changes and validation fails — which is why the format checker on this page can flag a typo from one wrong digit.
What makes a Swiss IBAN valid
A Switzerland IBAN is structurally valid only when it passes three independent checks at once. First, the character set: the first two characters must be the letters CH, the next two must be digits, and the BBAN may contain only digits and uppercase letters. Second, the length: a CH IBAN must be exactly 21 characters, because Switzerland fixes its BBAN at 17 characters and ISO 13616 fixes the country code and check digits at four. Third, the MOD 97 checksum. The 5!n12!c pattern adds one more layer — it confirms the BBAN splits into 2 fields of the right size and type, so a Switzerland IBAN with the right total length but the wrong internal split still fails. This is why the format checker on this page is stricter than a generic length-only check.
Common Swiss IBAN format mistakes
Most Switzerland IBAN format errors come from a handful of avoidable mistakes. Pasting a domestic Switzerland account number instead of the IBAN is the most common — the IBAN always starts with CH and is 21 characters, while a local account number is usually shorter and has no country prefix. Dropping or adding a character when copying from a statement is next; because the length is fixed, even one extra digit fails. Confusing the country code with a similar one (for example CH vs a neighbor) changes both the expected length and the check digits, so the whole IBAN fails. Finally, including spaces in the stored value is harmless for validation but can break payment forms that count characters literally — strip spaces before you submit a CH IBAN to a wire form.
Swiss IBAN and SWIFT codes
When you send or receive an international payment to Switzerland, the IBAN tells the network which account to credit, and the bank's SWIFT/BIC code tells it which bank holds that account. After checking the CH IBAN format here, open the Switzerland SWIFT codes page to find the receiving bank's BIC and complete the wire instructions.