diff --git a/main/src/main/java/org/mobilitydata/gtfsvalidator/validator/BookingRulesEntityValidator.java b/main/src/main/java/org/mobilitydata/gtfsvalidator/validator/BookingRulesEntityValidator.java
new file mode 100644
index 0000000000..0c7983b2c6
--- /dev/null
+++ b/main/src/main/java/org/mobilitydata/gtfsvalidator/validator/BookingRulesEntityValidator.java
@@ -0,0 +1,86 @@
+package org.mobilitydata.gtfsvalidator.validator;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.mobilitydata.gtfsvalidator.annotation.GtfsValidationNotice;
+import org.mobilitydata.gtfsvalidator.annotation.GtfsValidationNotice.FileRefs;
+import org.mobilitydata.gtfsvalidator.annotation.GtfsValidator;
+import org.mobilitydata.gtfsvalidator.notice.NoticeContainer;
+import org.mobilitydata.gtfsvalidator.notice.SeverityLevel;
+import org.mobilitydata.gtfsvalidator.notice.ValidationNotice;
+import org.mobilitydata.gtfsvalidator.table.GtfsBookingRules;
+import org.mobilitydata.gtfsvalidator.table.GtfsBookingRulesSchema;
+import org.mobilitydata.gtfsvalidator.table.GtfsBookingType;
+
+@GtfsValidator
+public class BookingRulesEntityValidator extends SingleEntityValidator<GtfsBookingRules> {
+
+  @Override
+  public void validate(GtfsBookingRules entity, NoticeContainer noticeContainer) {
+    // Only validate entities with REALTIME booking type
+    if (entity.bookingType() != GtfsBookingType.REALTIME) {
+      return;
+    }
+
+    // Retrieve the list of forbidden fields
+    List<String> forbiddenFields = findForbiddenRealTimeFields(entity);
+
+    // If there are any forbidden fields, add a validation notice
+    if (!forbiddenFields.isEmpty()) {
+      noticeContainer.addValidationNotice(
+          new ForbiddenRealTimeBookingFieldValueNotice(entity, forbiddenFields));
+    }
+  }
+
+  /** Finds forbidden fields that should not be present for real-time booking rules. */
+  public static List<String> findForbiddenRealTimeFields(GtfsBookingRules bookingRule) {
+    List<String> fields = new ArrayList<>();
+
+    // Check each field and add its name to the list if it's present
+    if (bookingRule.hasPriorNoticeDurationMin()) {
+      fields.add(GtfsBookingRules.PRIOR_NOTICE_DURATION_MIN_FIELD_NAME);
+    }
+    if (bookingRule.hasPriorNoticeDurationMax()) {
+      fields.add(GtfsBookingRules.PRIOR_NOTICE_DURATION_MAX_FIELD_NAME);
+    }
+    if (bookingRule.hasPriorNoticeLastDay()) {
+      fields.add(GtfsBookingRules.PRIOR_NOTICE_LAST_DAY_FIELD_NAME);
+    }
+    if (bookingRule.hasPriorNoticeLastTime()) {
+      fields.add(GtfsBookingRules.PRIOR_NOTICE_LAST_TIME_FIELD_NAME);
+    }
+    if (bookingRule.hasPriorNoticeStartDay()) {
+      fields.add(GtfsBookingRules.PRIOR_NOTICE_START_DAY_FIELD_NAME);
+    }
+    if (bookingRule.hasPriorNoticeStartTime()) {
+      fields.add(GtfsBookingRules.PRIOR_NOTICE_START_TIME_FIELD_NAME);
+    }
+    if (bookingRule.hasPriorNoticeServiceId()) {
+      fields.add(GtfsBookingRules.PRIOR_NOTICE_SERVICE_ID_FIELD_NAME);
+    }
+
+    return fields;
+  }
+
+  /** A forbidden field value is present for a real-time booking rule in `booking_rules.txt`. */
+  @GtfsValidationNotice(
+      severity = SeverityLevel.ERROR,
+      files = @FileRefs(GtfsBookingRulesSchema.class))
+  static class ForbiddenRealTimeBookingFieldValueNotice extends ValidationNotice {
+    /** The row number of the faulty record. */
+    private final int csvRowNumber;
+
+    /** The `booking_rules.booking_rule_id` of the faulty record. */
+    private final String bookingRuleId;
+
+    /** The names of the forbidden fields comma-separated. */
+    private final String fieldNames;
+
+    ForbiddenRealTimeBookingFieldValueNotice(
+        GtfsBookingRules bookingRule, List<String> forbiddenFields) {
+      this.csvRowNumber = bookingRule.csvRowNumber();
+      this.bookingRuleId = bookingRule.bookingRuleId();
+      this.fieldNames = String.join(", ", forbiddenFields);
+    }
+  }
+}
diff --git a/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/BookingRulesEntityValidatorTest.java b/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/BookingRulesEntityValidatorTest.java
new file mode 100644
index 0000000000..98ba39b459
--- /dev/null
+++ b/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/BookingRulesEntityValidatorTest.java
@@ -0,0 +1,92 @@
+package org.mobilitydata.gtfsvalidator.validator;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.mobilitydata.gtfsvalidator.table.GtfsBookingType.REALTIME;
+
+import java.util.List;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.mobilitydata.gtfsvalidator.notice.NoticeContainer;
+import org.mobilitydata.gtfsvalidator.notice.ValidationNotice;
+import org.mobilitydata.gtfsvalidator.table.GtfsBookingRules;
+import org.mobilitydata.gtfsvalidator.table.GtfsBookingType;
+import org.mobilitydata.gtfsvalidator.type.GtfsTime;
+import org.mobilitydata.gtfsvalidator.validator.BookingRulesEntityValidator.ForbiddenRealTimeBookingFieldValueNotice;
+
+@RunWith(JUnit4.class)
+public class BookingRulesEntityValidatorTest {
+
+  private static List<ValidationNotice> generateNotices(GtfsBookingRules bookingRule) {
+    NoticeContainer noticeContainer = new NoticeContainer();
+    BookingRulesEntityValidator validator = new BookingRulesEntityValidator();
+    validator.validate(bookingRule, noticeContainer);
+    return noticeContainer.getValidationNotices();
+  }
+
+  @Test
+  public void realTimeBookingWithForbiddenFieldsShouldGenerateNotice() {
+    GtfsBookingRules bookingRule =
+        new GtfsBookingRules.Builder()
+            .setCsvRowNumber(1)
+            .setBookingRuleId("rule-1")
+            .setBookingType(REALTIME)
+            .setPriorNoticeDurationMin(30) // Forbidden field
+            .setPriorNoticeLastDay(2) // Forbidden field
+            .build();
+
+    assertThat(generateNotices(bookingRule))
+        .containsExactly(
+            new ForbiddenRealTimeBookingFieldValueNotice(
+                bookingRule,
+                List.of(
+                    GtfsBookingRules.PRIOR_NOTICE_DURATION_MIN_FIELD_NAME,
+                    GtfsBookingRules.PRIOR_NOTICE_LAST_DAY_FIELD_NAME)));
+  }
+
+  @Test
+  public void realTimeBookingWithoutForbiddenFieldsShouldNotGenerateNotice() {
+    GtfsBookingRules bookingRule =
+        new GtfsBookingRules.Builder()
+            .setCsvRowNumber(1)
+            .setBookingRuleId("rule-2")
+            .setBookingType(REALTIME)
+            .build();
+
+    assertThat(generateNotices(bookingRule)).isEmpty();
+  }
+
+  @Test
+  public void scheduledBookingShouldNotGenerateNotice() {
+    GtfsBookingRules bookingRule =
+        new GtfsBookingRules.Builder()
+            .setCsvRowNumber(1)
+            .setBookingRuleId("rule-3")
+            .setBookingType(GtfsBookingType.SAMEDAY)
+            .build();
+
+    assertThat(generateNotices(bookingRule)).isEmpty();
+  }
+
+  @Test
+  public void realTimeBookingWithMultipleForbiddenFieldsShouldGenerateNotice() {
+    GtfsBookingRules bookingRule =
+        new GtfsBookingRules.Builder()
+            .setCsvRowNumber(1)
+            .setBookingRuleId("rule-4")
+            .setBookingType(REALTIME)
+            .setPriorNoticeDurationMax(60) // Forbidden field
+            .setPriorNoticeStartTime(GtfsTime.fromSecondsSinceMidnight(2)) // Forbidden field
+            .setPriorNoticeServiceId("service-1") // Forbidden field
+            .build();
+
+    assertThat(generateNotices(bookingRule))
+        .containsExactly(
+            new ForbiddenRealTimeBookingFieldValueNotice(
+                bookingRule,
+                List.of(
+                    GtfsBookingRules.PRIOR_NOTICE_DURATION_MAX_FIELD_NAME,
+                    GtfsBookingRules.PRIOR_NOTICE_START_TIME_FIELD_NAME,
+                    GtfsBookingRules.PRIOR_NOTICE_SERVICE_ID_FIELD_NAME)));
+  }
+}
diff --git a/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/NoticeFieldsTest.java b/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/NoticeFieldsTest.java
index 0e55eda83f..3ce85cb493 100644
--- a/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/NoticeFieldsTest.java
+++ b/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/NoticeFieldsTest.java
@@ -199,7 +199,9 @@ public void testNoticeClassFieldNames() {
             "pathwayMode",
             "isBidirectional",
             "locationGroupId",
-            "locationId");
+            "locationId",
+            "bookingRuleId",
+            "fieldNames");
   }
 
   private static List<String> discoverValidationNoticeFieldNames() {