diff --git a/services/payments/src/test/java/com/klaro/bais/payments/PaymentReferenceServiceTest.java b/services/payments/src/test/java/com/klaro/bais/payments/PaymentReferenceServiceTest.java
new file mode 100644
index 0000000..aabd8c6
--- /dev/null
+++ b/services/payments/src/test/java/com/klaro/bais/payments/PaymentReferenceServiceTest.java
@@ -0,0 +1,27 @@
+package com.klaro.bais.payments;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class PaymentReferenceServiceTest {
+
+    private final PaymentReferenceService service = new PaymentReferenceService();
+
+    @Test
+    void testNormalizeWithNull() {
+        String result = service.normalize(null);
+        assertEquals("", result);
+    }
+
+    @Test
+    void testNormalizeWithWhitespace() {
+        String result = service.normalize(" ");
+        assertEquals("");
+    }
+
+    @Test
+    void testNormalizeWithNormalString() {
+        String result = service.normalize(" Test String ");
+        assertEquals("Test String", result);
+    }
+}