diff --git a/src/backend/api/routers/setup.py b/src/backend/api/routers/setup.py
index b9c4aaa..39767ff 100644
--- a/src/backend/api/routers/setup.py
+++ b/src/backend/api/routers/setup.py
@@ -6,7 +6,7 @@ NOT protected by API Key auth (standalone access).
 import hmac
 import random
 from datetime import datetime, timedelta
-from src.backend.utils.tempo import utcnow
+from src.backend.utils.tempo import iso_utc, utcnow
 from pathlib import Path
 
 from alembic import command
@@ -604,8 +604,8 @@ async def list_users(body: PasswordBody):
                     "roles": u.roles or [],
                     "is_admin": u.is_admin,
                     "active": u.active,
-                    "created_at": u.created_at.isoformat() if u.created_at else None,
-                    "last_login": u.last_login.isoformat() if u.last_login else None,
+                    "created_at": iso_utc(u.created_at) or None,
+                    "last_login": iso_utc(u.last_login) or None,
                 }
                 for u in users
             ],
diff --git a/src/backend/services/report_service.py b/src/backend/services/report_service.py
index a5ded88..975a41d 100644
--- a/src/backend/services/report_service.py
+++ b/src/backend/services/report_service.py
@@ -33,6 +33,11 @@ _jinja_env = Environment(
 )
 
 
+def _giorno_locale(dt: datetime) -> str:
+    """UTC naive filter bound -> local calendar day (YYYY-MM-DD)."""
+    return to_local(dt).strftime("%Y-%m-%d")
+
+
 async def _query_measurements(
     db: AsyncSession,
     recipe_id: int,
@@ -324,9 +329,9 @@ async def generate_spc_report(
     if version_id:
         filters_desc.append(f"Version: {version_id}")
     if date_from:
-        filters_desc.append(f"From: {date_from.strftime('%Y-%m-%d')}")
+        filters_desc.append(f"From: {_giorno_locale(date_from)}")
     if date_to:
-        filters_desc.append(f"To: {date_to.strftime('%Y-%m-%d')}")
+        filters_desc.append(f"To: {_giorno_locale(date_to)}")
     if lot_number:
         filters_desc.append(f"Lot: {lot_number}")
     if serial_number:
@@ -415,9 +420,9 @@ async def generate_measurement_report(
     if version_id:
         filters_desc.append(f"Version: {version_id}")
     if date_from:
-        filters_desc.append(f"From: {date_from.strftime('%Y-%m-%d')}")
+        filters_desc.append(f"From: {_giorno_locale(date_from)}")
     if date_to:
-        filters_desc.append(f"To: {date_to.strftime('%Y-%m-%d')}")
+        filters_desc.append(f"To: {_giorno_locale(date_to)}")
     if lot_number:
         filters_desc.append(f"Lot: {lot_number}")
     if serial_number:
diff --git a/src/backend/tests/test_tempo.py b/src/backend/tests/test_tempo.py
index 98b5eb5..3107a5e 100644
--- a/src/backend/tests/test_tempo.py
+++ b/src/backend/tests/test_tempo.py
@@ -106,3 +106,8 @@ async def test_report_generated_at_is_local_time(
         await report_service.generate_measurement_report(db_session, recipe.id)
 
     assert "Generated 2026-10-06 10:00" in captured["html"]
+
+
+def test_report_filter_day_is_local():
+    """UTC naive 22:00 of Oct 5 is already Oct 6 in Europe/Rome (#42)."""
+    assert report_service._giorno_locale(datetime(2026, 10, 5, 22, 0, 0)) == "2026-10-06"