diff --git a/cli/src/main/java/org/mobilitydata/gtfsvalidator/cli/Arguments.java b/cli/src/main/java/org/mobilitydata/gtfsvalidator/cli/Arguments.java
index d7dda065c0..d79bfbfeeb 100644
--- a/cli/src/main/java/org/mobilitydata/gtfsvalidator/cli/Arguments.java
+++ b/cli/src/main/java/org/mobilitydata/gtfsvalidator/cli/Arguments.java
@@ -21,6 +21,8 @@
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.nio.file.Path;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
 import org.mobilitydata.gtfsvalidator.input.CountryCode;
 import org.mobilitydata.gtfsvalidator.runner.ValidationRunnerConfig;
 
@@ -52,6 +54,14 @@ public class Arguments {
               + "It must be a two-letter country code (ISO 3166-1 alpha-2)")
   private String countryCode;
 
+  @Parameter(
+      names = {"-d", "--date"},
+      description =
+          "Date to simulate when validating, in ISO_LOCAL_DATE format like "
+              + "'2001-01-30'. By default, the current date is used. "
+              + "This option enables debugging rules like feed expiration.")
+  private String dateString;
+
   @Parameter(
       names = {"-u", "--url"},
       description = "Fully qualified URL to download GTFS archive")
@@ -111,6 +121,9 @@ ValidationRunnerConfig toConfig() throws URISyntaxException {
     if (countryCode != null) {
       builder.setCountryCode(CountryCode.forStringOrUnknown(countryCode));
     }
+    if (dateString != null) {
+      builder.setDateForValidation(LocalDate.parse(dateString, DateTimeFormatter.ISO_LOCAL_DATE));
+    }
     if (validationReportName != null) {
       builder.setValidationReportFileName(validationReportName);
     }
diff --git a/cli/src/test/java/org/mobilitydata/gtfsvalidator/cli/ArgumentsTest.java b/cli/src/test/java/org/mobilitydata/gtfsvalidator/cli/ArgumentsTest.java
index 795215c72a..4cba280185 100644
--- a/cli/src/test/java/org/mobilitydata/gtfsvalidator/cli/ArgumentsTest.java
+++ b/cli/src/test/java/org/mobilitydata/gtfsvalidator/cli/ArgumentsTest.java
@@ -87,7 +87,8 @@ public void longNameShouldInitializeArguments() throws URISyntaxException {
       "--input", "/tmp/gtfs.zip",
       "--output_base", "/tmp/output",
       "--country_code", "ca",
-      "--threads", "4"
+      "--threads", "4",
+      "--date", "2020-01-02"
     };
 
     Arguments underTest = new Arguments();
@@ -100,6 +101,7 @@ public void longNameShouldInitializeArguments() throws URISyntaxException {
     assertThat(config.validationReportFileName()).matches("report.json");
     assertThat(config.htmlReportFileName()).matches("report.html");
     assertThat(config.systemErrorsReportFileName()).matches("system_errors.json");
+    assertThat(config.dateForValidation().toString()).matches("2020-01-02");
   }
 
   @Test
diff --git a/main/src/main/java/org/mobilitydata/gtfsvalidator/report/HtmlReportGenerator.java b/main/src/main/java/org/mobilitydata/gtfsvalidator/report/HtmlReportGenerator.java
index 0cdef7acf4..3d72409b8a 100644
--- a/main/src/main/java/org/mobilitydata/gtfsvalidator/report/HtmlReportGenerator.java
+++ b/main/src/main/java/org/mobilitydata/gtfsvalidator/report/HtmlReportGenerator.java
@@ -39,7 +39,8 @@ public void generateReport(
       ValidationRunnerConfig config,
       VersionInfo versionInfo,
       Path reportPath,
-      String date)
+      String date,
+      boolean is_different_date)
       throws IOException {
     TemplateEngine templateEngine = new TemplateEngine();
     ClassLoaderTemplateResolver templateResolver = new ClassLoaderTemplateResolver();
@@ -54,6 +55,7 @@ public void generateReport(
     context.setVariable("summary", summary);
     context.setVariable("config", config);
     context.setVariable("date", date);
+    context.setVariable("is_different_date", is_different_date);
 
     try (FileWriter writer = new FileWriter(reportPath.toFile())) {
       templateEngine.process("report.html", context, writer);
diff --git a/main/src/main/java/org/mobilitydata/gtfsvalidator/report/JsonReportSummary.java b/main/src/main/java/org/mobilitydata/gtfsvalidator/report/JsonReportSummary.java
index 8ee69ae308..08470a1ca3 100644
--- a/main/src/main/java/org/mobilitydata/gtfsvalidator/report/JsonReportSummary.java
+++ b/main/src/main/java/org/mobilitydata/gtfsvalidator/report/JsonReportSummary.java
@@ -29,6 +29,7 @@ public class JsonReportSummary {
   private String validationReportName;
   private String htmlReportName;
   private String countryCode;
+  private String dateForValidation;
   private JsonReportFeedInfo feedInfo;
   private List<JsonReportAgencyMetadata> agencies;
   private Set<String> files;
@@ -55,6 +56,7 @@ public JsonReportSummary(
       this.validationReportName = config.validationReportFileName();
       this.htmlReportName = config.htmlReportFileName();
       this.countryCode = config.countryCode().getCountryCode();
+      this.dateForValidation = config.dateForValidation().toString();
     } else {
       logger.atSevere().log(
           "No validation configuration for JSON report, there will be missing data in the report.");
diff --git a/main/src/main/java/org/mobilitydata/gtfsvalidator/runner/ValidationRunner.java b/main/src/main/java/org/mobilitydata/gtfsvalidator/runner/ValidationRunner.java
index ad5fae0960..51a7f61734 100644
--- a/main/src/main/java/org/mobilitydata/gtfsvalidator/runner/ValidationRunner.java
+++ b/main/src/main/java/org/mobilitydata/gtfsvalidator/runner/ValidationRunner.java
@@ -25,10 +25,9 @@
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Paths;
-import java.text.SimpleDateFormat;
 import java.time.Duration;
-import java.time.LocalDate;
-import java.util.Date;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
 import java.util.List;
 import java.util.stream.Collectors;
 import org.mobilitydata.gtfsvalidator.input.DateForValidation;
@@ -120,7 +119,7 @@ public Status run(ValidationRunnerConfig config) {
     ValidationContext validationContext =
         ValidationContext.builder()
             .setCountryCode(config.countryCode())
-            .setDateForValidation(new DateForValidation(LocalDate.now()))
+            .setDateForValidation(new DateForValidation(config.dateForValidation()))
             .build();
     try {
       feedContainer =
@@ -267,9 +266,9 @@ public static void exportReport(
             "Error creating output directory: %s", config.outputDirectory());
       }
     }
-    SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd 'at' HH:mm:ss z");
-    Date now = new Date(System.currentTimeMillis());
-    String date = formatter.format(now);
+    ZonedDateTime now = ZonedDateTime.now();
+    String date = now.format(DateTimeFormatter.ofPattern("yyyy-MM-dd 'at' HH:mm:ss z"));
+    boolean is_different_date = !now.toLocalDate().equals(config.dateForValidation());
 
     Gson gson = createGson(config.prettyJson());
     HtmlReportGenerator htmlGenerator = new HtmlReportGenerator();
@@ -291,7 +290,8 @@ public static void exportReport(
           config,
           versionInfo,
           config.outputDirectory().resolve(config.htmlReportFileName()),
-          date);
+          date,
+          is_different_date);
       Files.write(
           config.outputDirectory().resolve(config.systemErrorsReportFileName()),
           gson.toJson(noticeContainer.exportSystemErrors()).getBytes(StandardCharsets.UTF_8));
diff --git a/main/src/main/java/org/mobilitydata/gtfsvalidator/runner/ValidationRunnerConfig.java b/main/src/main/java/org/mobilitydata/gtfsvalidator/runner/ValidationRunnerConfig.java
index 2fc9d52c67..9eea19bb65 100644
--- a/main/src/main/java/org/mobilitydata/gtfsvalidator/runner/ValidationRunnerConfig.java
+++ b/main/src/main/java/org/mobilitydata/gtfsvalidator/runner/ValidationRunnerConfig.java
@@ -18,6 +18,7 @@
 import com.google.auto.value.AutoValue;
 import java.net.URI;
 import java.nio.file.Path;
+import java.time.LocalDate;
 import java.util.Optional;
 import org.mobilitydata.gtfsvalidator.input.CountryCode;
 
@@ -56,6 +57,9 @@ public Path systemErrorsReportPath() {
   // validated.
   public abstract CountryCode countryCode();
 
+  // The date to use for validation.
+  public abstract LocalDate dateForValidation();
+
   // If true, any output json will be pretty-printed.
   public abstract boolean prettyJson();
 
@@ -67,7 +71,8 @@ public static Builder builder() {
         .setSystemErrorsReportFileName("system_errors.json")
         .setNumThreads(1)
         .setPrettyJson(false)
-        .setCountryCode(CountryCode.forStringOrUnknown(CountryCode.ZZ));
+        .setCountryCode(CountryCode.forStringOrUnknown(CountryCode.ZZ))
+        .setDateForValidation(LocalDate.now());
   }
 
   @AutoValue.Builder
@@ -88,6 +93,8 @@ public abstract static class Builder {
 
     public abstract Builder setCountryCode(CountryCode countryCode);
 
+    public abstract Builder setDateForValidation(LocalDate dateForValidation);
+
     public abstract Builder setPrettyJson(boolean prettyJson);
 
     public abstract ValidationRunnerConfig build();
diff --git a/main/src/main/resources/report.html b/main/src/main/resources/report.html
index 6c1d1256c8..f95a71d3b0 100644
--- a/main/src/main/resources/report.html
+++ b/main/src/main/resources/report.html
@@ -229,6 +229,7 @@ <h1>GTFS Schedule Validation Report</h1>
         <span th:text="${config.gtfsSource}"></span><span
                 th:text="${config.countryCode.isUnknown()} ? '. No country code was provided.' : ', with the country code: ' + ${config.countryCode} + '.'"></span>
         </br>
+        <span th:if="${is_different_date}" th:text="'The date used during validation was ' + ${config.dateForValidation} + '.'"></span></p>
 
     <p>Use this report alongside our <a href="https://gtfs-validator.mobilitydata.org/rules.html">documentation</a>.</p>
 
diff --git a/main/src/test/java/org/mobilitydata/gtfsvalidator/report/model/JsonReportSummaryTest.java b/main/src/test/java/org/mobilitydata/gtfsvalidator/report/model/JsonReportSummaryTest.java
index c9587c34d7..0c6fedea7d 100644
--- a/main/src/test/java/org/mobilitydata/gtfsvalidator/report/model/JsonReportSummaryTest.java
+++ b/main/src/test/java/org/mobilitydata/gtfsvalidator/report/model/JsonReportSummaryTest.java
@@ -9,6 +9,7 @@
 import com.google.gson.JsonParser;
 import java.net.URI;
 import java.nio.file.Path;
+import java.time.LocalDate;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Map;
@@ -41,6 +42,7 @@ private static ValidationRunnerConfig generateValidationRunnerConfig() throws Ex
     builder.setPrettyJson(true);
     builder.setSystemErrorsReportFileName("some_error_filename");
     builder.setValidationReportFileName("some_report_filename");
+    builder.setDateForValidation(LocalDate.parse("2020-01-02"));
 
     return builder.build();
   }
@@ -91,7 +93,8 @@ public void noFeedMetadataWithConfigTest() throws Exception {
             + "\"systemErrorsReportName\":\"some_error_filename\","
             + "\"validationReportName\":\"some_report_filename\","
             + "\"htmlReportName\":\"some_html_filename\","
-            + "\"countryCode\":\"GB\"}";
+            + "\"countryCode\":\"GB\","
+            + "\"dateForValidation\":\"2020-01-02\"}";
 
     assertEquals(JsonParser.parseString(expected), gson.toJsonTree(reportSummary));
   }
@@ -113,6 +116,7 @@ public void withFeedMetadataWithConfigTest() throws Exception {
             + "\"validationReportName\":\"some_report_filename\","
             + "\"htmlReportName\":\"some_html_filename\","
             + "\"countryCode\":\"GB\","
+            + "\"dateForValidation\":\"2020-01-02\","
             + "\"feedInfo\":{\"publisherName\":\"value1\",\"publisherUrl\":\"value2\"},"
             + "\"agencies\":["
             + "{\"name\":\"agency1\",\"url\":\"some URL 1\",\"phone\":\"phone1\",\"email\":\"email1\"},"