diff --git a/.changeset/fresh-otters-count.md b/.changeset/fresh-otters-count.md
new file mode 100644
index 0000000..f9f9420
--- /dev/null
+++ b/.changeset/fresh-otters-count.md
@@ -0,0 +1,5 @@
+---
+'@obosbbl/format': minor
+---
+
+Add Norwegian account number formatting.
diff --git a/packages/format/README.md b/packages/format/README.md
index 9b35131..2e49275 100644
--- a/packages/format/README.md
+++ b/packages/format/README.md
@@ -43,5 +43,6 @@ formatOrganizationNumber('0000000000') // => '000000-0000'
 
 * formatPhoneNumber
 * formatOrganizationNumber
+* formatAccountNumber
 * formatObosMembershipNumber
 * formatPostalCode
diff --git a/packages/format/src/format.test.ts b/packages/format/src/format.test.ts
index db3a649..db4b2bd 100644
--- a/packages/format/src/format.test.ts
+++ b/packages/format/src/format.test.ts
@@ -1,5 +1,6 @@
 import { describe, expect, test } from 'vitest';
 import {
+  formatAccountNumber as formatAccountNumberNo,
   formatObosMembershipNumber as formatObosMembershipNumberNo,
   formatOrganizationNumber as formatOrganizationNumberNo,
   formatPhoneNumber as formatPhoneNumberNo,
@@ -31,6 +32,15 @@ describe('no', () => {
     expect(formatOrganizationNumberNo(input)).toBe(expected);
   });
 
+  test.each([
+    ['00000000000', '0000 00 00000'],
+    ['0000 00 00000', '0000 00 00000'],
+    ['0000.00.00000', '0000 00 00000'],
+    ['abc', 'abc'],
+  ])('formatAccountNumber(%s) -> %s', (input, expected) => {
+    expect(formatAccountNumberNo(input)).toBe(expected);
+  });
+
   test.each([['0000', '0000']])(
     'formatPostalCode(%s) -> %s',
     (input, expected) => {
diff --git a/packages/format/src/index.ts b/packages/format/src/index.ts
index e89391b..4e09b2c 100644
--- a/packages/format/src/index.ts
+++ b/packages/format/src/index.ts
@@ -1,4 +1,5 @@
 import {
+  formatAccountNumber as _formatAccountNumber,
   formatObosMembershipNumber as _formatObosMembershipNumber,
   formatOrganizationNumber as formatOrganizationNumberNo,
   formatPhoneNumber as formatPhoneNumberNo,
@@ -16,6 +17,10 @@ type Options = {
   locale: Locale;
 };
 
+type NorwegianOptions = {
+  locale: 'no';
+};
+
 /**
  * Format a phone number.
  *
@@ -51,6 +56,21 @@ export function formatOrganizationNumber(
     : formatOrganizationNumberSe(input);
 }
 
+/**
+ * Format a Norwegian account number
+ * @example
+ * ```
+ * formatAccountNumber('00000000000', { locale: 'no' }) // => '0000 00 00000'
+ * ```
+ */
+export function formatAccountNumber(
+  input: string,
+  options: NorwegianOptions,
+): string {
+  // This is currently a Norwegian-only formatter. Keep the options argument for API consistency.
+  return _formatAccountNumber(input);
+}
+
 /**
  * Format a postal code
  * @example
diff --git a/packages/format/src/no.ts b/packages/format/src/no.ts
index 9e59471..c087dfc 100644
--- a/packages/format/src/no.ts
+++ b/packages/format/src/no.ts
@@ -52,6 +52,19 @@ export function formatOrganizationNumber(input: string): string {
   return replaceIfMatch(input, ORG_NUMBER_FORMAT, '$1 $2 $3');
 }
 
+const ACCOUNT_NUMBER_FORMAT = /^(\d{4})(\d{2})(\d{5})$/;
+
+/**
+ * Format a Norwegian account number
+ * @example
+ * ```
+ * formatAccountNumber('00000000000') // => '0000 00 00000'
+ * ```
+ */
+export function formatAccountNumber(input: string): string {
+  return replaceIfMatch(input, ACCOUNT_NUMBER_FORMAT, '$1 $2 $3');
+}
+
 const OBOS_MEMBERSHIP_NUMBER_FORMAT = /^(\d{3})(\d{2})(\d{2})$/;
 
 /**