diff --git a/CRM/Event/BAO/Participant.php b/CRM/Event/BAO/Participant.php
index 1f19c32f74b4..f18198b20961 100644
--- a/CRM/Event/BAO/Participant.php
+++ b/CRM/Event/BAO/Participant.php
@@ -1877,7 +1877,6 @@ public static function formatFieldsAndSetProfileDefaults($contactId, &$form) {
    * Evaluate whether a participant record is eligible for self-service transfer/cancellation.  If so,
    * return additional participant/event details.
    *
-   * TODO: This function fails when the "hours until self-service" is less than zero.
    * @param int $participantId
    * @param string $url
    * @param bool $isBackOffice
@@ -1930,7 +1929,12 @@ public static function getSelfServiceEligibility(int $participantId, string $url
       $cancelDeadline = (new Datetime($start_date))->sub($cancelInterval);
       if ($timenow > $cancelDeadline) {
         $details['eligible'] = FALSE;
-        $details['ineligible_message'] = ts("Registration for this event cannot be cancelled or transferred less than %1 hours prior to the event's start time. Contact the event organizer if you have questions.", [1 => $time_limit]);
+        // Change the language of the status message based on whether the waitlist time limit is positive or negative.
+        $afterOrPrior = $time_limit < 0 ? 'after' : 'prior';
+        $moreOrLess = $time_limit < 0 ? 'more' : 'less';
+        $details['ineligible_message'] = ts("Registration for this event cannot be cancelled or transferred %1 than %2 hours %3 to the event's start time. Contact the event organizer if you have questions.",
+        [1 => $moreOrLess, 2 => $cancelHours, 3 => $afterOrPrior]);
+
       }
     }
     return $details;
diff --git a/CRM/Event/DAO/Event.php b/CRM/Event/DAO/Event.php
index adcf39c5d7aa..742de59cf45b 100644
--- a/CRM/Event/DAO/Event.php
+++ b/CRM/Event/DAO/Event.php
@@ -6,7 +6,7 @@
  *
  * Generated from xml/schema/CRM/Event/Event.xml
  * DO NOT EDIT.  Generated by CRM_Core_CodeGen
- * (GenCodeChecksum:331a210ceb36b5e9460705dbfbe71abf)
+ * (GenCodeChecksum:5f01b2be07ae960dffdbaa5249f23783)
  */
 
 /**
diff --git a/CRM/Upgrade/Incremental/sql/5.29.alpha1.mysql.tpl b/CRM/Upgrade/Incremental/sql/5.29.alpha1.mysql.tpl
index 18b176d4b0f0..487d949dc604 100644
--- a/CRM/Upgrade/Incremental/sql/5.29.alpha1.mysql.tpl
+++ b/CRM/Upgrade/Incremental/sql/5.29.alpha1.mysql.tpl
@@ -45,3 +45,6 @@ SET body_text = '{ts escape="sql" 1=$unsubgroup 2=$actresub 3=$actresuburl}You h
 WHERE component_type  = 'Unsubscribe'
 AND (body_text = '{ts escape="sql" 1=$unsubgroup 2=$actresub}You have been un-subscribed from the following groups: %1. You can re-subscribe by mailing %2 or clicking %3{/ts}'
   OR body_text = '{ts escape="sql" 1=$unsubgroup 2=$actresub}You have been un-subscribed from the following groups: %1. You can re-subscribe by mailing %2 or clicking {/ts}');
+
+-- Allow self-service/transfer to have a negative time.
+ALTER TABLE civicrm_event MODIFY COLUMN selfcancelxfer_time INT;
diff --git a/tests/phpunit/CRM/Event/BAO/ParticipantTest.php b/tests/phpunit/CRM/Event/BAO/ParticipantTest.php
index eb8dc5700842..4dc15134dc0a 100644
--- a/tests/phpunit/CRM/Event/BAO/ParticipantTest.php
+++ b/tests/phpunit/CRM/Event/BAO/ParticipantTest.php
@@ -493,6 +493,15 @@ public function selfServiceScenarios() {
       'isBackOffice' => FALSE,
       'successExpected' => FALSE,
     ];
+    // Cancellation deadline is < 0 hours
+    $scenarios[] = [
+      'selfSvcEnabled' => 1,
+      'selfSvcHours' => -12,
+      'hoursToEvent' => 4,
+      'participantStatusId' => 1,
+      'isBackOffice' => FALSE,
+      'successExpected' => TRUE,
+    ];
     return $scenarios;
   }
 
diff --git a/xml/schema/Event/Event.xml b/xml/schema/Event/Event.xml
index d4c9c65299df..60ec46b0ef8d 100644
--- a/xml/schema/Event/Event.xml
+++ b/xml/schema/Event/Event.xml
@@ -679,7 +679,7 @@
   </field>
   <field>
     <name>selfcancelxfer_time</name>
-    <type>int unsigned</type>
+    <type>int</type>
     <default>0</default>
     <title>Self-service Cancellation or Transfer Time</title>
     <comment>Number of hours prior to event start date to allow self-service cancellation or transfer.</comment>