diff --git a/backend/main.py b/backend/main.py
index 6b5ad32..efe67da 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -705,13 +705,17 @@ def calculate_attendance_status(check_in, check_out, shift_start, shift_end):
             expected_end_dt = datetime.combine(check_out_dt.date(), shift_end)
         
         if check_out_dt < expected_end_dt:
-            diff = (expected_end_dt - check_out_dt).total_seconds() / 60
-            result["early_minutes"] = round(diff)
+            diff_seconds = (expected_end_dt - check_out_dt).total_seconds()
+            result["early_minutes"] = round(diff_seconds / 60) if diff_seconds >= 30 else 0
     
     # Calculate OT minutes (leaving after scheduled end)
     if check_out_dt > expected_end_dt:
-        diff = (check_out_dt - expected_end_dt).total_seconds() / 60
-        result["ot_minutes"] = round(diff)
+        diff_seconds = (check_out_dt - expected_end_dt).total_seconds()
+        # Ignore tiny differences (< 30 seconds) to avoid floating-point noise
+        if diff_seconds >= 30:
+            result["ot_minutes"] = round(diff_seconds / 60)
+        else:
+            result["ot_minutes"] = 0
     
     # Determine status code and text
     status_parts = []