diff --git a/scripts/pr_quality/check_pr.py b/scripts/pr_quality/check_pr.py
index e1991e46d361..2cf225a27aac 100644
--- a/scripts/pr_quality/check_pr.py
+++ b/scripts/pr_quality/check_pr.py
@@ -470,10 +470,18 @@ def main(
             pr_number,
         )
         return
+    if commit_count == 0:
+        logger.info(
+            "PR #%s author has no commits -- setting size threshold to 0.",
+            pr_number,
+        )
+        threshold = 0
+    else:
+        threshold = LARGE_PR_THRESHOLD
 
     pr_title_result = SKIPPED
     total_changes = get_pr_total_changes(pr_number, repo, token)
-    ticket_result = check_trac_ticket(pr_body, total_changes)
+    ticket_result = check_trac_ticket(pr_body, total_changes, threshold)
     ticket_status_result = SKIPPED
     ticket_has_patch_result = SKIPPED
     ticket_id = extract_ticket_id(pr_body) if ticket_result is None else None
diff --git a/scripts/pr_quality/errors.py b/scripts/pr_quality/errors.py
index cd305868ac37..cd41612da341 100644
--- a/scripts/pr_quality/errors.py
+++ b/scripts/pr_quality/errors.py
@@ -154,6 +154,7 @@ def as_details(self, level=LEVEL_ERROR):
     "Patches submitted against unreviewed tickets are unlikely to be merged.\n"
     "3. Edit the **Trac ticket number** section of your PR description to include "
     "the ticket in the format `ticket-NNNNN` (e.g. `ticket-36991`).\n\n"
-    "For PRs with fewer than {threshold} lines changed (additions + deletions), you "
-    "may write `N/A` in the ticket field instead (e.g. `N/A - typo fix`).",
+    "Unless this is your first contribution, for PRs with fewer than {threshold} lines "
+    "changed (additions + deletions), you may write `N/A` in the ticket field instead "
+    "(e.g. `N/A - typo fix`).",
 )
diff --git a/scripts/pr_quality/tests/test_check_pr.py b/scripts/pr_quality/tests/test_check_pr.py
index 30bfa26512aa..0aff15ca109b 100644
--- a/scripts/pr_quality/tests/test_check_pr.py
+++ b/scripts/pr_quality/tests/test_check_pr.py
@@ -770,6 +770,15 @@ def test_established_author_skips_all_checks(self):
         self.assertIsNone(result)
         mock_gh.assert_not_called()
 
+    def test_new_contributor_cannot_omit_ticket(self):
+        body = make_pr_body(ticket="", checked_items=0)
+        _, mock_summary, _ = self.call_main(pr_body=body, commit_count=0)
+        _, results, _ = mock_summary.call_args.args
+        result_map = {name: result for name, result, _ in results}
+        self.assertEqual(
+            result_map["Trac ticket referenced"].title, check_pr.MISSING_TRAC_TICKET[0]
+        )
+
     def test_fully_valid_pr_no_comment_posted(self):
         result, _, mock_gh = self.call_main(
             pr_body=VALID_PR_BODY, pr_title=VALID_PR_TITLE