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..ee30f15
--- /dev/null
+++ b/services/payments/src/test/java/com/klaro/bais/payments/PaymentReferenceServiceTest.java
@@ -0,0 +1,28 @@
+package com.klaro.bais.payments;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class PaymentReferenceServiceTest {
+    private final PaymentReferenceService paymentReferenceService = new PaymentReferenceService();
+
+    @Test
+    void testNormalize_NullInput() {
+        assertEquals("", paymentReferenceService.normalize(null));
+    }
+
+    @Test
+    void testNormalize_EmptyInput() {
+        assertEquals("", paymentReferenceService.normalize(""));
+    }
+
+    @Test
+    void testNormalize_WhitespaceInput() {
+        assertEquals("", paymentReferenceService.normalize("   "));
+    }
+
+    @Test
+    void testNormalize_RegularInput() {
+        assertEquals("Hello", paymentReferenceService.normalize(" Hello "));
+    }
+}