diff --git a/common/src/main/java/de/ozgcloud/eingang/common/vorgang/VorgangNummerSupplier.java b/common/src/main/java/de/ozgcloud/eingang/common/vorgang/VorgangNummerSupplier.java
index 1c6c26979e5d5c0e58c3d3b939890fb433555c89..510b7c92779fa39758cf3da4855a7af4dec20fe1 100644
--- a/common/src/main/java/de/ozgcloud/eingang/common/vorgang/VorgangNummerSupplier.java
+++ b/common/src/main/java/de/ozgcloud/eingang/common/vorgang/VorgangNummerSupplier.java
@@ -1,7 +1,6 @@
 package de.ozgcloud.eingang.common.vorgang;
 
 import java.time.LocalDate;
-import java.util.Random;
 
 import org.apache.commons.lang3.RandomStringUtils;
 import org.springframework.stereotype.Component;
@@ -12,18 +11,15 @@ import lombok.RequiredArgsConstructor;
 @RequiredArgsConstructor
 public class VorgangNummerSupplier {
 
-	static final String VORGANGNUMMER_TEMPLATE = "%d%02X%02d-%s";
+	static final String VORGANGNUMMER_TEMPLATE = "%d%X%02d-%s";
 	static final char[] BASE30_ALPHABET = { '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'M',
 			'N', 'P', 'Q', 'R', 'S', 'T', 'V', 'W', 'X', 'Y', 'Z' };
 	static final int SUFFIX_LENGTH = 6;
-	static final int NEXT_MAX_HEX_NUMBER = 256;
-
-	private final Random randomGenerator = new Random();
 
 	public String get() {
 		var today = LocalDate.now();
 		var lastYearNumber = today.getYear() % 10;
-		return VORGANGNUMMER_TEMPLATE.formatted(lastYearNumber, randomGenerator.nextInt(NEXT_MAX_HEX_NUMBER), today.getDayOfMonth(),
+		return VORGANGNUMMER_TEMPLATE.formatted(lastYearNumber, today.getMonthValue(), today.getDayOfMonth(),
 				RandomStringUtils.random(SUFFIX_LENGTH, BASE30_ALPHABET));
 	}
 
diff --git a/common/src/test/java/de/ozgcloud/eingang/common/vorgang/VorgangNummerSupplierTest.java b/common/src/test/java/de/ozgcloud/eingang/common/vorgang/VorgangNummerSupplierTest.java
index 3ae655895f61f58158803bb5bbfd16f94b55ca8e..2fc9a524f5e23d2bebd9721eb5612d96ad879782 100644
--- a/common/src/test/java/de/ozgcloud/eingang/common/vorgang/VorgangNummerSupplierTest.java
+++ b/common/src/test/java/de/ozgcloud/eingang/common/vorgang/VorgangNummerSupplierTest.java
@@ -20,15 +20,13 @@ class VorgangNummerSupplierTest {
 	@InjectMocks
 	private VorgangNummerSupplier vorgangNummerSupplier;
 
-	@Mock
-	private Random randomGenerator;
 
 	@Test
 	@DisplayName("should add random suffix of length 6")
 	void shouldAddSuffix() {
 		var result = vorgangNummerSupplier.get();
 
-		assertThat(result).hasSize(12);
+		assertThat(result).hasSize(11);
 	}
 
 	@Test
@@ -44,7 +42,7 @@ class VorgangNummerSupplierTest {
 	void shouldHaveSize() {
 		var result = vorgangNummerSupplier.get();
 
-		assertThat(getPrefix(result)).hasSize(6);
+		assertThat(getPrefix(result)).hasSize(5);
 	}
 
 	private String getPrefix(String string) {
@@ -62,14 +60,11 @@ class VorgangNummerSupplierTest {
 
 	@Test
 	void shouldAddMonthValueSecond() {
-		var value = 244;
-		var hexValue = "F4";
-		when(randomGenerator.nextInt(anyInt())).thenReturn(value);
-		ReflectionTestUtils.setField(vorgangNummerSupplier, "randomGenerator", randomGenerator);
+		var monthHexValue = "%X".formatted(LocalDate.now().getMonthValue());
 
 		var result = vorgangNummerSupplier.get();
 
-		assertThat(result.substring(1, 3)).isEqualTo(hexValue);
+		assertThat(result.substring(1, 2)).isEqualTo(monthHexValue);
 	}
 
 	@Test
@@ -78,14 +73,14 @@ class VorgangNummerSupplierTest {
 
 		var result = vorgangNummerSupplier.get();
 
-		assertThat(result.substring(3, 5)).isEqualTo(dayValue);
+		assertThat(result.substring(2, 4)).isEqualTo(dayValue);
 	}
 
 	@Test
 	void shouldAddHyphenAtEnd() {
 		var result = vorgangNummerSupplier.get();
 
-		assertThat(result.charAt(5)).isEqualTo('-');
+		assertThat(result.charAt(4)).isEqualTo('-');
 	}
 
 }
\ No newline at end of file