diff --git a/.pylintrc b/.pylintrc
index 838f62f78..38e63ae1a 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -93,7 +93,8 @@ disable=raw-checker-failed,
         logging-fstring-interpolation,
         broad-exception-raised,
         use-dict-literal,
-        use-implicit-booleaness-not-comparison
+        use-implicit-booleaness-not-comparison,
+        too-many-return-statements
 
 
 
diff --git a/server/activity_log/slack_worker.py b/server/activity_log/slack_worker.py
index 15dfd0c96..b89fafba4 100644
--- a/server/activity_log/slack_worker.py
+++ b/server/activity_log/slack_worker.py
@@ -11,7 +11,6 @@
 from ..sentry import configure_sentry
 
 
-# pylint: disable=too-many-return-statements
 def slack_message(activity: activity_log.Activity):
     base = activity.base
     org_link = urljoin(config.HTTP_ORIGIN, f"/support/orgs/{base.organization_id}")
diff --git a/server/api/shared.py b/server/api/shared.py
index d887e6a17..d95e3a1c1 100644
--- a/server/api/shared.py
+++ b/server/api/shared.py
@@ -526,15 +526,32 @@ def ballot_vote_deltas(
     if reported is None:
         reported = {choice.id: "0" for choice in contest.choices}
 
-    deltas = {}
-    for choice in contest.choices:
-        reported_vote = (
-            0 if reported[choice.id] in ["o", "u"] else int(reported[choice.id])
-        )
-        audited_vote = (
-            0 if audited[choice.id] in ["o", "u"] else int(audited[choice.id])
-        )
-        deltas[choice.id] = reported_vote - audited_vote
+    # Special case for ES&S overvotes/undervotes.
+    has_overvote = "o" in reported.values()
+    has_undervote = "u" in reported.values()
+    audited_votes = sum(map(int, (audited.values())))
+    # If the audited result correctly identified overvote/undervote, return no
+    # delta. Otherwise, return discrepancies as usual, but substituting in
+    # overvotes/undervotes.
+    if has_overvote:
+        if audited_votes > 1:
+            return None
+        else:
+            deltas = {
+                choice.id: 1 - int(audited[choice.id]) for choice in contest.choices
+            }
+    elif has_undervote:
+        if audited_votes < 1:
+            return None
+        else:
+            deltas = {
+                choice.id: 0 - int(audited[choice.id]) for choice in contest.choices
+            }
+    else:
+        deltas = {
+            choice.id: int(reported[choice.id]) - int(audited[choice.id])
+            for choice in contest.choices
+        }
 
     if all(delta == 0 for delta in deltas.values()):
         return None
diff --git a/server/tests/ballot_comparison/snapshots/snap_test_ballot_comparison.py b/server/tests/ballot_comparison/snapshots/snap_test_ballot_comparison.py
index 1548d5381..b5ea4b6c5 100644
--- a/server/tests/ballot_comparison/snapshots/snap_test_ballot_comparison.py
+++ b/server/tests/ballot_comparison/snapshots/snap_test_ballot_comparison.py
@@ -55,8 +55,8 @@
 J1,0002,BATCH2,5,0002000175,"Round 1: 0.128937575131137250, 0.240487859312182291",AUDITED,Choice 1-2,Choice 1-2,,,Choice 2-2,Choice 2-2,,\r
 J2,0001,BATCH1,1,0001013415,Round 1: 0.228946820159681463,AUDITED,"Choice 1-1, INVALID_WRITE_IN",Choice 1-1,,,"Choice 2-1, INVALID_WRITE_IN",Choice 2-1,,\r
 J2,0001,BATCH1,3,0001013417,Round 1: 0.457121710197159606,AUDITED,Choice 1-1,Choice 1-1,,,Choice 2-1,Choice 2-1,,\r
-J2,0001,BATCH2,3,0001000417,Round 1: 0.269793733438455805,AUDITED,"Choice 1-1, Choice 1-2",Overvote,Choice 1-1: -1; Choice 1-2: -1,,"Choice 2-1, Choice 2-3",Overvote,Choice 2-1: -1; Choice 2-3: -1,\r
-J2,0002,BATCH1,3,0002003173,Round 1: 0.328294241227374952,AUDITED,Choice 1-2,Overvote,Choice 1-2: -1,1,Choice 2-2,Overvote,Choice 2-2: -1,1\r
+J2,0001,BATCH2,3,0001000417,Round 1: 0.269793733438455805,AUDITED,"Choice 1-1, Choice 1-2",Overvote,,,"Choice 2-1, Choice 2-3",Overvote,,\r
+J2,0002,BATCH1,3,0002003173,Round 1: 0.328294241227374952,AUDITED,Choice 1-2,Overvote,Choice 1-1: +1,1,Choice 2-2,Overvote,Choice 2-1: +1; Choice 2-3: +1,1\r
 J2,0002,BATCH2,1,0002000171,Round 1: 0.390715133294243377,AUDITED,Choice 1-1,Choice 1-1,,,Choice 2-3,Choice 2-3,,\r
 J2,0002,BATCH2,2,0002000172,Round 1: 0.064290634474137509,AUDITED,Choice 1-1,Choice 1-1,,,Choice 2-3,Choice 2-3,,\r
 J2,0002,BATCH2,5,0002000175,Round 1: 0.212277542626930704,AUDITED,Choice 1-1,Choice 1-1,,,Choice 2-3,Choice 2-3,,\r