diff --git a/src/__tests__/numbering.test.ts b/src/__tests__/numbering.test.ts
new file mode 100644
index 0000000..e948f72
--- /dev/null
+++ b/src/__tests__/numbering.test.ts
@@ -0,0 +1,18 @@
+import { describe, it, expect } from 'vitest';
+import { generateSharedNumber, generateOfferNumber } from '../services/numbering.service';
+
+describe('generateSharedNumber', () => {
+  it('returns correct format (YYtypeCode + 4 digits)', async () => {
+    const num = await generateSharedNumber();
+    const yy = String(new Date().getFullYear()).slice(-2);
+    expect(num).toMatch(new RegExp(`^${yy}\\d{2,}\\d{4}$`));
+  });
+});
+
+describe('generateOfferNumber', () => {
+  it('returns correct format (YEAR/PREFIX/NNN)', async () => {
+    const num = await generateOfferNumber();
+    const year = new Date().getFullYear();
+    expect(num).toMatch(new RegExp(`^${year}/[A-Z]+/\\d{3,}$`));
+  });
+});