From 738d1acd381b2cdba923df49c0296619610dbc02 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Wed, 27 Aug 2025 10:49:19 +0200
Subject: [PATCH 01/18] Add string utility function
 isValidSwissSocialSecurityNumber

---
 CHANGELOG.md           |  4 ++++
 src/lib/string.spec.ts | 12 +++++++++++-
 src/lib/string.ts      | 31 +++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c15e1c6..ec8feb5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- `isValidSwissSocialSecurityNumber` string utility function
+
 ## [2.0.0] - 2025-07-29
 
 ### Added
diff --git a/src/lib/string.spec.ts b/src/lib/string.spec.ts
index 94fc71e..7162223 100644
--- a/src/lib/string.spec.ts
+++ b/src/lib/string.spec.ts
@@ -1,4 +1,4 @@
-import { isNullOrEmpty, isNullOrWhitespace, capitalize, uncapitalize, truncate } from "./string";
+import { isNullOrEmpty, isNullOrWhitespace, capitalize, uncapitalize, truncate, isValidSwissSocialSecurityNumber } from "./string";
 
 describe("string tests", () => {
   test.each([
@@ -120,4 +120,14 @@ describe("string tests", () => {
   ])("truncate without suffix parameter", (value, maxLength, expected) => {
     expect(truncate(value, maxLength)).toBe(expected);
   });
+
+  test.each([
+    [null as unknown as string, false],
+    [undefined as unknown as string, false],
+    ["7569217076985", false],
+    ["756.9217.0769.85", true],
+    ["756.1234.5678.99", false],
+  ])("check if ahv number is valid or not", (ahvNumber, expected) => {
+    expect(isValidSwissSocialSecurityNumber(ahvNumber)).toBe(expected);
+  });
 });
diff --git a/src/lib/string.ts b/src/lib/string.ts
index c0666b3..fadbc98 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -64,3 +64,34 @@ export function truncate(value: string | undefined, maxLength: number, suffix =
 
   return `${value.slice(0, maxLength)}${suffix}`;
 }
+
+/**
+ * Validation of Social insurance number with regex and checking of checksum
+ * Validation according to https://www.sozialversicherungsnummer.ch/aufbau-neu.htm
+ * @param socialInsuranceNumber The social insurance number to check
+ * @returns the result if the social insurance number is valid or not
+ */
+export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string): boolean {
+  const regex = new RegExp(/[7][5][6][.][\d]{4}[.][\d]{4}[.][\d]{2}$/);
+  if (regex.test(socialInsuranceNumber) && !isNullOrEmpty(socialInsuranceNumber)) {
+    //todo check checksum
+    const number = socialInsuranceNumber.slice(0, -1);
+
+    const reversedNumber = [...number.split(".").join("")].reverse().join("");
+    const reversedNumberArray = [...reversedNumber];
+    let sum = 0;
+    for (const [i, element] of reversedNumberArray.entries()) {
+      sum += i % 2 === 0 ? Number(element) * 3 : Number(element) * 1;
+    }
+
+    const checksum = Math.ceil(sum / 10) * 10 - sum;
+    const checknumber = Number.parseInt(socialInsuranceNumber.slice(-1));
+
+    if (checksum !== checknumber) {
+      return false;
+    }
+    return true;
+  } else {
+    return false;
+  }
+}

From 4aac36e5fc853fdf09836496f869d987e9c23abb Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Wed, 27 Aug 2025 15:41:17 +0200
Subject: [PATCH 02/18] Add:ed that AHV number doesn't have to be formatted
 already to get checked

---
 src/lib/string.spec.ts | 4 +++-
 src/lib/string.ts      | 9 ++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/lib/string.spec.ts b/src/lib/string.spec.ts
index 7162223..d6d296c 100644
--- a/src/lib/string.spec.ts
+++ b/src/lib/string.spec.ts
@@ -124,9 +124,11 @@ describe("string tests", () => {
   test.each([
     [null as unknown as string, false],
     [undefined as unknown as string, false],
-    ["7569217076985", false],
+    ["7569217076985", true],
     ["756.9217.0769.85", true],
     ["756.1234.5678.99", false],
+    ["7561234567899", false],
+    ["7000000000000", false],
   ])("check if ahv number is valid or not", (ahvNumber, expected) => {
     expect(isValidSwissSocialSecurityNumber(ahvNumber)).toBe(expected);
   });
diff --git a/src/lib/string.ts b/src/lib/string.ts
index fadbc98..3c0d129 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -72,9 +72,9 @@ export function truncate(value: string | undefined, maxLength: number, suffix =
  * @returns the result if the social insurance number is valid or not
  */
 export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string): boolean {
-  const regex = new RegExp(/[7][5][6][.][\d]{4}[.][\d]{4}[.][\d]{2}$/);
-  if (regex.test(socialInsuranceNumber) && !isNullOrEmpty(socialInsuranceNumber)) {
-    //todo check checksum
+  if (!isNullOrEmpty(socialInsuranceNumber)) {
+    const compactInsuranceNumber = socialInsuranceNumber.replaceAll(/[\s.]+/g, "");
+    if (!/^756\d{10}$/.test(compactInsuranceNumber)) return false;
     const number = socialInsuranceNumber.slice(0, -1);
 
     const reversedNumber = [...number.split(".").join("")].reverse().join("");
@@ -91,7 +91,6 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
       return false;
     }
     return true;
-  } else {
-    return false;
   }
+  return false;
 }

From 32b3b2cb6943263dd0bcdabaac9996a9f346fd5a Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Wed, 27 Aug 2025 15:42:53 +0200
Subject: [PATCH 03/18] Changed comments

---
 src/lib/string.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/lib/string.ts b/src/lib/string.ts
index 3c0d129..8bb2163 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -66,10 +66,10 @@ export function truncate(value: string | undefined, maxLength: number, suffix =
 }
 
 /**
- * Validation of Social insurance number with regex and checking of checksum
+ * Validation of Social insurance number with checking the checksum
  * Validation according to https://www.sozialversicherungsnummer.ch/aufbau-neu.htm
  * @param socialInsuranceNumber The social insurance number to check
- * @returns the result if the social insurance number is valid or not
+ * @returns The result if the social insurance number is valid or not
  */
 export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string): boolean {
   if (!isNullOrEmpty(socialInsuranceNumber)) {

From 36175859a418ccb4705faf4ab9ba815220bb34bb Mon Sep 17 00:00:00 2001
From: "Sandro C." <sc@neolution.ch>
Date: Wed, 27 Aug 2025 15:59:50 +0200
Subject: [PATCH 04/18] Update src/lib/string.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
---
 src/lib/string.ts | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/lib/string.ts b/src/lib/string.ts
index 8bb2163..c2c1844 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -87,10 +87,7 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
     const checksum = Math.ceil(sum / 10) * 10 - sum;
     const checknumber = Number.parseInt(socialInsuranceNumber.slice(-1));
 
-    if (checksum !== checknumber) {
-      return false;
-    }
-    return true;
+    return checksum === checknumber;
   }
   return false;
 }

From b6323b4766effb0e84e7514d5a7dd2dddd3a143b Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Wed, 27 Aug 2025 16:04:52 +0200
Subject: [PATCH 05/18] Fix

---
 src/lib/string.ts | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/src/lib/string.ts b/src/lib/string.ts
index 8bb2163..fea9204 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -75,7 +75,7 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
   if (!isNullOrEmpty(socialInsuranceNumber)) {
     const compactInsuranceNumber = socialInsuranceNumber.replaceAll(/[\s.]+/g, "");
     if (!/^756\d{10}$/.test(compactInsuranceNumber)) return false;
-    const number = socialInsuranceNumber.slice(0, -1);
+    const number = compactInsuranceNumber.slice(0, -1);
 
     const reversedNumber = [...number.split(".").join("")].reverse().join("");
     const reversedNumberArray = [...reversedNumber];
@@ -84,13 +84,10 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
       sum += i % 2 === 0 ? Number(element) * 3 : Number(element) * 1;
     }
 
-    const checksum = Math.ceil(sum / 10) * 10 - sum;
-    const checknumber = Number.parseInt(socialInsuranceNumber.slice(-1));
+    const checksum = (10 - (sum % 10)) % 10;
+    const checknumber = Number.parseInt(compactInsuranceNumber.slice(-1));
 
-    if (checksum !== checknumber) {
-      return false;
-    }
-    return true;
+    return checksum === checknumber;
   }
   return false;
 }

From f7a4a547d4deb3f3609f0e3ce7093d3a7216a611 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Wed, 27 Aug 2025 16:16:03 +0200
Subject: [PATCH 06/18] Fix

---
 src/lib/string.ts | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/src/lib/string.ts b/src/lib/string.ts
index fea9204..f09a296 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -72,22 +72,23 @@ export function truncate(value: string | undefined, maxLength: number, suffix =
  * @returns The result if the social insurance number is valid or not
  */
 export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string): boolean {
-  if (!isNullOrEmpty(socialInsuranceNumber)) {
-    const compactInsuranceNumber = socialInsuranceNumber.replaceAll(/[\s.]+/g, "");
-    if (!/^756\d{10}$/.test(compactInsuranceNumber)) return false;
-    const number = compactInsuranceNumber.slice(0, -1);
-
-    const reversedNumber = [...number.split(".").join("")].reverse().join("");
-    const reversedNumberArray = [...reversedNumber];
-    let sum = 0;
-    for (const [i, element] of reversedNumberArray.entries()) {
-      sum += i % 2 === 0 ? Number(element) * 3 : Number(element) * 1;
-    }
+  if (isNullOrEmpty(socialInsuranceNumber)) {
+    return false;
+  }
+  const compactInsuranceNumber = socialInsuranceNumber.replaceAll(/[\s.]+/g, "");
+  if (!/^756\d{10}$/.test(compactInsuranceNumber)) {
+    return false;
+  }
+  const number = compactInsuranceNumber.slice(0, -1);
+  const reversedNumber = [...number.split(".").join("")].reverse().join("");
+  const reversedNumberArray = [...reversedNumber];
+  let sum = 0;
+  for (const [i, element] of reversedNumberArray.entries()) {
+    sum += i % 2 === 0 ? Number(element) * 3 : Number(element) * 1;
+  }
 
-    const checksum = (10 - (sum % 10)) % 10;
-    const checknumber = Number.parseInt(compactInsuranceNumber.slice(-1));
+  const checksum = (10 - (sum % 10)) % 10;
+  const checknumber = Number.parseInt(compactInsuranceNumber.slice(-1));
 
-    return checksum === checknumber;
-  }
-  return false;
+  return checksum === checknumber;
 }

From 761cb3d22186889381591b36d1918c8e19405a7e Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Wed, 27 Aug 2025 16:47:46 +0200
Subject: [PATCH 07/18] Changed AHV number in test

---
 src/lib/string.spec.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/lib/string.spec.ts b/src/lib/string.spec.ts
index d6d296c..6551f63 100644
--- a/src/lib/string.spec.ts
+++ b/src/lib/string.spec.ts
@@ -126,8 +126,8 @@ describe("string tests", () => {
     [undefined as unknown as string, false],
     ["7569217076985", true],
     ["756.9217.0769.85", true],
-    ["756.1234.5678.99", false],
-    ["7561234567899", false],
+    ["756.1234.5678.91", false],
+    ["7561234567891", false],
     ["7000000000000", false],
   ])("check if ahv number is valid or not", (ahvNumber, expected) => {
     expect(isValidSwissSocialSecurityNumber(ahvNumber)).toBe(expected);

From 7762b6c3453bb29c1416cd4837a58ab88495a9d3 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Wed, 27 Aug 2025 17:04:26 +0200
Subject: [PATCH 08/18] Fix

---
 src/lib/string.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lib/string.ts b/src/lib/string.ts
index f09a296..3d6dd4f 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -80,7 +80,7 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
     return false;
   }
   const number = compactInsuranceNumber.slice(0, -1);
-  const reversedNumber = [...number.split(".").join("")].reverse().join("");
+  const reversedNumber = [...number].reverse().join("");
   const reversedNumberArray = [...reversedNumber];
   let sum = 0;
   for (const [i, element] of reversedNumberArray.entries()) {

From 0df21661a6c3435d6aa462d8c9444da59f9eff72 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Thu, 28 Aug 2025 07:40:21 +0200
Subject: [PATCH 09/18] Changed to is null or whitespace check

---
 src/lib/string.spec.ts | 2 ++
 src/lib/string.ts      | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/lib/string.spec.ts b/src/lib/string.spec.ts
index 6551f63..6495401 100644
--- a/src/lib/string.spec.ts
+++ b/src/lib/string.spec.ts
@@ -127,6 +127,8 @@ describe("string tests", () => {
     ["7569217076985", true],
     ["756.9217.0769.85", true],
     ["756.1234.5678.91", false],
+    ["7 5......69 2...1707......69.85", true],
+    ["7 5......61 2...3456......7......89 1", false],
     ["7561234567891", false],
     ["7000000000000", false],
   ])("check if ahv number is valid or not", (ahvNumber, expected) => {
diff --git a/src/lib/string.ts b/src/lib/string.ts
index 3d6dd4f..415cb44 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -72,7 +72,7 @@ export function truncate(value: string | undefined, maxLength: number, suffix =
  * @returns The result if the social insurance number is valid or not
  */
 export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string): boolean {
-  if (isNullOrEmpty(socialInsuranceNumber)) {
+  if (isNullOrWhitespace(socialInsuranceNumber)) {
     return false;
   }
   const compactInsuranceNumber = socialInsuranceNumber.replaceAll(/[\s.]+/g, "");

From 84ccdff11dfd58661bd032325f58667e51fc2955 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Thu, 28 Aug 2025 08:38:38 +0200
Subject: [PATCH 10/18] Add IBAN to check now must be in one of two valid
 formats

---
 src/lib/string.spec.ts |  8 ++++----
 src/lib/string.ts      | 25 +++++++++++++++++--------
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/src/lib/string.spec.ts b/src/lib/string.spec.ts
index 6495401..b96dee7 100644
--- a/src/lib/string.spec.ts
+++ b/src/lib/string.spec.ts
@@ -125,13 +125,13 @@ describe("string tests", () => {
     [null as unknown as string, false],
     [undefined as unknown as string, false],
     ["7569217076985", true],
+    ["7561234567891", false],
     ["756.9217.0769.85", true],
     ["756.1234.5678.91", false],
-    ["7 5......69 2...1707......69.85", true],
+    ["756.1234.5678.91", false],
+    ["7 5......69 2...1707......69.85", false],
     ["7 5......61 2...3456......7......89 1", false],
-    ["7561234567891", false],
-    ["7000000000000", false],
-  ])("check if ahv number is valid or not", (ahvNumber, expected) => {
+  ])("check if the social insurance number is valid or not", (ahvNumber, expected) => {
     expect(isValidSwissSocialSecurityNumber(ahvNumber)).toBe(expected);
   });
 });
diff --git a/src/lib/string.ts b/src/lib/string.ts
index 415cb44..8bd96c5 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -66,29 +66,38 @@ export function truncate(value: string | undefined, maxLength: number, suffix =
 }
 
 /**
- * Validation of Social insurance number with checking the checksum
+ * Validation of social insurance number with checking the checksum
  * Validation according to https://www.sozialversicherungsnummer.ch/aufbau-neu.htm
  * @param socialInsuranceNumber The social insurance number to check
+ * Must be in one of the following formats:
+ * - "756.XXXX.XXXX.XX" with dots as seperators
+ * - "756XXXXXXXXXX" with digits only
  * @returns The result if the social insurance number is valid or not
  */
 export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string): boolean {
   if (isNullOrWhitespace(socialInsuranceNumber)) {
     return false;
   }
-  const compactInsuranceNumber = socialInsuranceNumber.replaceAll(/[\s.]+/g, "");
-  if (!/^756\d{10}$/.test(compactInsuranceNumber)) {
+
+  const socialInsuranceNumberWithDots = new RegExp(/[7][5][6][.][\d]{4}[.][\d]{4}[.][\d]{2}$/);
+  const socialInsuranceNumberWithoutDots = new RegExp(/^756\d{10}$/);
+
+  if (!socialInsuranceNumberWithDots.test(socialInsuranceNumber) && !socialInsuranceNumberWithoutDots.test(socialInsuranceNumber)) {
     return false;
   }
-  const number = compactInsuranceNumber.slice(0, -1);
-  const reversedNumber = [...number].reverse().join("");
-  const reversedNumberArray = [...reversedNumber];
+
+  const compactNumber = socialInsuranceNumber.replaceAll(/[\s.]+/g, "");
+  const digits = compactNumber.slice(0, -1);
+  const reversedDigits = [...digits].reverse().join("");
+  const reversedDigitsArray = [...reversedDigits];
+
   let sum = 0;
-  for (const [i, element] of reversedNumberArray.entries()) {
+  for (const [i, element] of reversedDigitsArray.entries()) {
     sum += i % 2 === 0 ? Number(element) * 3 : Number(element) * 1;
   }
 
   const checksum = (10 - (sum % 10)) % 10;
-  const checknumber = Number.parseInt(compactInsuranceNumber.slice(-1));
+  const checknumber = Number.parseInt(compactNumber.slice(-1));
 
   return checksum === checknumber;
 }

From 211261805b8d779d1d8b20062eed579bcc16e826 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Thu, 28 Aug 2025 10:32:46 +0200
Subject: [PATCH 11/18] Add new regexp schema

---
 src/lib/string.spec.ts | 1 +
 src/lib/string.ts      | 3 +--
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/lib/string.spec.ts b/src/lib/string.spec.ts
index b96dee7..0cbeb8f 100644
--- a/src/lib/string.spec.ts
+++ b/src/lib/string.spec.ts
@@ -127,6 +127,7 @@ describe("string tests", () => {
     ["7569217076985", true],
     ["7561234567891", false],
     ["756.9217.0769.85", true],
+    ["test756.9217.0769.85", false],
     ["756.1234.5678.91", false],
     ["756.1234.5678.91", false],
     ["7 5......69 2...1707......69.85", false],
diff --git a/src/lib/string.ts b/src/lib/string.ts
index 8bd96c5..fe57615 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -79,13 +79,12 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
     return false;
   }
 
-  const socialInsuranceNumberWithDots = new RegExp(/[7][5][6][.][\d]{4}[.][\d]{4}[.][\d]{2}$/);
+  const socialInsuranceNumberWithDots = new RegExp(/^756.\d{4}.\d{4}.\d{2}$/);
   const socialInsuranceNumberWithoutDots = new RegExp(/^756\d{10}$/);
 
   if (!socialInsuranceNumberWithDots.test(socialInsuranceNumber) && !socialInsuranceNumberWithoutDots.test(socialInsuranceNumber)) {
     return false;
   }
-
   const compactNumber = socialInsuranceNumber.replaceAll(/[\s.]+/g, "");
   const digits = compactNumber.slice(0, -1);
   const reversedDigits = [...digits].reverse().join("");

From c775711e6e495b7eba228f2fd25b88fa66aecd80 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Thu, 28 Aug 2025 11:11:56 +0200
Subject: [PATCH 12/18] Add replace only the dot out of the number

---
 src/lib/string.spec.ts | 9 ++++-----
 src/lib/string.ts      | 2 +-
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/lib/string.spec.ts b/src/lib/string.spec.ts
index 0cbeb8f..4a97de1 100644
--- a/src/lib/string.spec.ts
+++ b/src/lib/string.spec.ts
@@ -124,14 +124,13 @@ describe("string tests", () => {
   test.each([
     [null as unknown as string, false],
     [undefined as unknown as string, false],
-    ["7569217076985", true],
     ["7561234567891", false],
+    ["7569217076985", true],
     ["756.9217.0769.85", true],
-    ["test756.9217.0769.85", false],
+    ["756..9217.0769.85", false],
     ["756.1234.5678.91", false],
-    ["756.1234.5678.91", false],
-    ["7 5......69 2...1707......69.85", false],
-    ["7 5......61 2...3456......7......89 1", false],
+    ["test756.9217.0769.85", false],
+    ["7.56..9217...0769.85", false],
   ])("check if the social insurance number is valid or not", (ahvNumber, expected) => {
     expect(isValidSwissSocialSecurityNumber(ahvNumber)).toBe(expected);
   });
diff --git a/src/lib/string.ts b/src/lib/string.ts
index fe57615..ef02c3a 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -85,7 +85,7 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
   if (!socialInsuranceNumberWithDots.test(socialInsuranceNumber) && !socialInsuranceNumberWithoutDots.test(socialInsuranceNumber)) {
     return false;
   }
-  const compactNumber = socialInsuranceNumber.replaceAll(/[\s.]+/g, "");
+  const compactNumber = socialInsuranceNumber.replaceAll(".", "");
   const digits = compactNumber.slice(0, -1);
   const reversedDigits = [...digits].reverse().join("");
   const reversedDigitsArray = [...reversedDigits];

From 90b40970491ea728f88463b511b90f0a0c8893dd Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Thu, 28 Aug 2025 15:09:07 +0200
Subject: [PATCH 13/18] Add comment how to check the social insurance number

---
 src/lib/string.ts | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/src/lib/string.ts b/src/lib/string.ts
index ef02c3a..fb72f12 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -79,12 +79,29 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
     return false;
   }
 
-  const socialInsuranceNumberWithDots = new RegExp(/^756.\d{4}.\d{4}.\d{2}$/);
-  const socialInsuranceNumberWithoutDots = new RegExp(/^756\d{10}$/);
+  const socialInsuranceNumberWithDots = new RegExp(/^756.?\d{4}.?\d{4}.?\d{2}$/);
 
-  if (!socialInsuranceNumberWithDots.test(socialInsuranceNumber) && !socialInsuranceNumberWithoutDots.test(socialInsuranceNumber)) {
+  if (!socialInsuranceNumberWithDots.test(socialInsuranceNumber)) {
     return false;
   }
+
+  /**
+   * Validates a Swiss social security number (AHV number).
+   *
+   * Validation steps:
+   * - The number must start with `756`, be 13 digits long, and follow one of the accepted formats:
+   *   - `756.XXXX.XXXX.XX` or `756XXXXXXXXXX`.
+   * - Remove dots → 13 digits remain.
+   * - The last digit is the check digit.
+   * - To calculate the check digit:
+   *   - Take the first 12 digits and reverse them.
+   *   - Multiply digits at even positions by 3, and digits at odd positions by 1.
+   *   - Sum all results.
+   *   - Look at the last digit of the sum (sum % 10).
+   *   - The check digit is the value needed to reach the next multiple of 10.
+   * - The number is valid if this check digit matches the last digit.
+   */
+
   const compactNumber = socialInsuranceNumber.replaceAll(".", "");
   const digits = compactNumber.slice(0, -1);
   const reversedDigits = [...digits].reverse().join("");

From 3f2ee4bd34b1b80fb316edc1c161a7d20ccc2df9 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Thu, 28 Aug 2025 15:22:33 +0200
Subject: [PATCH 14/18] Fix spelling

---
 src/lib/string.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lib/string.ts b/src/lib/string.ts
index fb72f12..1ea2863 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -89,7 +89,7 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
    * Validates a Swiss social security number (AHV number).
    *
    * Validation steps:
-   * - The number must start with `756`, be 13 digits long, and follow one of the accepted formats:
+   * - The number must start with `756`, be 13 digits long and follow one of the accepted formats:
    *   - `756.XXXX.XXXX.XX` or `756XXXXXXXXXX`.
    * - Remove dots → 13 digits remain.
    * - The last digit is the check digit.

From 4fda01eebdf3dd45d97840cf0eb3ff980ca435b1 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Thu, 28 Aug 2025 15:37:15 +0200
Subject: [PATCH 15/18] Spelling

---
 src/lib/string.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/lib/string.ts b/src/lib/string.ts
index 1ea2863..8dbf1f6 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -89,8 +89,8 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
    * Validates a Swiss social security number (AHV number).
    *
    * Validation steps:
-   * - The number must start with `756`, be 13 digits long and follow one of the accepted formats:
-   *   - `756.XXXX.XXXX.XX` or `756XXXXXXXXXX`.
+   * - The number must start with 756, be 13 digits long and follow one of the accepted formats:
+   *   - "756.XXXX.XXXX.XX" or "756XXXXXXXXXX".
    * - Remove dots → 13 digits remain.
    * - The last digit is the check digit.
    * - To calculate the check digit:

From 22406ce6437732f69f565c120fda350e80bc25c7 Mon Sep 17 00:00:00 2001
From: "Sandro C." <sc@neolution.ch>
Date: Fri, 29 Aug 2025 14:40:33 +0200
Subject: [PATCH 16/18] Update src/lib/string.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
---
 src/lib/string.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lib/string.ts b/src/lib/string.ts
index 8dbf1f6..bfe17ac 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -70,7 +70,7 @@ export function truncate(value: string | undefined, maxLength: number, suffix =
  * Validation according to https://www.sozialversicherungsnummer.ch/aufbau-neu.htm
  * @param socialInsuranceNumber The social insurance number to check
  * Must be in one of the following formats:
- * - "756.XXXX.XXXX.XX" with dots as seperators
+ * - "756.XXXX.XXXX.XX" with dots as separators
  * - "756XXXXXXXXXX" with digits only
  * @returns The result if the social insurance number is valid or not
  */

From 46b68b84440f5e7bb6978cf384df78b191303abf Mon Sep 17 00:00:00 2001
From: Daniele Debernardi <drebrez@gmail.com>
Date: Mon, 1 Sep 2025 11:04:01 +0200
Subject: [PATCH 17/18] Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
---
 src/lib/string.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lib/string.ts b/src/lib/string.ts
index bfe17ac..61fc9c0 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -79,7 +79,7 @@ export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string):
     return false;
   }
 
-  const socialInsuranceNumberWithDots = new RegExp(/^756.?\d{4}.?\d{4}.?\d{2}$/);
+  const socialInsuranceNumberWithDots = new RegExp(/^756\.?\d{4}\.?\d{4}\.?\d{2}$/);
 
   if (!socialInsuranceNumberWithDots.test(socialInsuranceNumber)) {
     return false;

From 933ef62400552c343eea0e1e2e76168fed501d2e Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Mon, 1 Sep 2025 13:03:01 +0200
Subject: [PATCH 18/18] Add two schemas for social insurance number

---
 src/lib/string.spec.ts |  1 +
 src/lib/string.ts      | 46 +++++++++++++++++++++++++-----------------
 2 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/src/lib/string.spec.ts b/src/lib/string.spec.ts
index 4a97de1..f9049f8 100644
--- a/src/lib/string.spec.ts
+++ b/src/lib/string.spec.ts
@@ -126,6 +126,7 @@ describe("string tests", () => {
     [undefined as unknown as string, false],
     ["7561234567891", false],
     ["7569217076985", true],
+    ["756.92170769.85", false],
     ["756.9217.0769.85", true],
     ["756..9217.0769.85", false],
     ["756.1234.5678.91", false],
diff --git a/src/lib/string.ts b/src/lib/string.ts
index 61fc9c0..c14768c 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -75,45 +75,55 @@ export function truncate(value: string | undefined, maxLength: number, suffix =
  * @returns The result if the social insurance number is valid or not
  */
 export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string): boolean {
+  // 1. Check if input is empty or only whitespace
   if (isNullOrWhitespace(socialInsuranceNumber)) {
     return false;
   }
 
-  const socialInsuranceNumberWithDots = new RegExp(/^756\.?\d{4}\.?\d{4}\.?\d{2}$/);
+  /**
+   * 2. Check if input matches accepted formats:
+   *    - With dots: 756.XXXX.XXXX.XX
+   *    - Without dots: 756XXXXXXXXXX
+   */
+  const socialInsuranceNumberWithDots = new RegExp(/^756\.\d{4}\.\d{4}\.\d{2}$/);
+  const socialInsuranceNumberWithoutDots = new RegExp(/^756\d{10}$/);
 
-  if (!socialInsuranceNumberWithDots.test(socialInsuranceNumber)) {
+  if (!socialInsuranceNumberWithDots.test(socialInsuranceNumber) && !socialInsuranceNumberWithoutDots.test(socialInsuranceNumber)) {
     return false;
   }
 
+  // 3. Remove all dots → get a string of 13 digits
+  const compactNumber = socialInsuranceNumber.replaceAll(".", "");
+
   /**
-   * Validates a Swiss social security number (AHV number).
-   *
-   * Validation steps:
-   * - The number must start with 756, be 13 digits long and follow one of the accepted formats:
-   *   - "756.XXXX.XXXX.XX" or "756XXXXXXXXXX".
-   * - Remove dots → 13 digits remain.
-   * - The last digit is the check digit.
-   * - To calculate the check digit:
-   *   - Take the first 12 digits and reverse them.
-   *   - Multiply digits at even positions by 3, and digits at odd positions by 1.
-   *   - Sum all results.
-   *   - Look at the last digit of the sum (sum % 10).
-   *   - The check digit is the value needed to reach the next multiple of 10.
-   * - The number is valid if this check digit matches the last digit.
+   * 4. Separate digits for checksum calculation
+   *    - first 12 digits: used to calculate checksum
+   *    - last digit: actual check digit
    */
-
-  const compactNumber = socialInsuranceNumber.replaceAll(".", "");
   const digits = compactNumber.slice(0, -1);
   const reversedDigits = [...digits].reverse().join("");
   const reversedDigitsArray = [...reversedDigits];
 
+  /*
+   * 5. Calculate weighted sum for checksum
+   *    - Even positions (after reversing) ×3
+   *    - Odd positions ×1
+   */
   let sum = 0;
   for (const [i, element] of reversedDigitsArray.entries()) {
     sum += i % 2 === 0 ? Number(element) * 3 : Number(element) * 1;
   }
 
+  /*
+   * 6. Calculate expected check digit
+   *    - Check digit = value to reach next multiple of 10
+   */
   const checksum = (10 - (sum % 10)) % 10;
   const checknumber = Number.parseInt(compactNumber.slice(-1));
 
+  /*
+   * 7. Compare calculated check digit with actual last digit
+   *    - If equal → valid AHV number
+   */
   return checksum === checknumber;
 }