diff --git a/custom_components/national_grid/config_flow.py b/custom_components/national_grid/config_flow.py
index 42a9b5c..3683b9c 100644
--- a/custom_components/national_grid/config_flow.py
+++ b/custom_components/national_grid/config_flow.py
@@ -56,6 +56,9 @@ async def async_step_user(
                 _LOGGER.exception(exception)
                 _errors["base"] = "unknown"
             else:
+                if not self._accounts:
+                    _LOGGER.error("Login succeeded but no accounts returned")
+                    return self.async_abort(reason="no_accounts_found")
                 await self.async_set_unique_id(slugify(self._username))
                 self._abort_if_unique_id_configured()
 
@@ -135,6 +138,12 @@ async def async_step_reconfigure(
             except NationalGridError as exception:
                 _LOGGER.exception(exception)
                 _errors["base"] = "unknown"
+            else:
+                if not self._accounts:
+                    _LOGGER.error(
+                        "Reconfigure: login succeeded but no accounts returned"
+                    )
+                    return self.async_abort(reason="no_accounts_found")
 
         current_selection = reconfigure_entry.data.get(CONF_SELECTED_ACCOUNTS, [])
 
diff --git a/custom_components/national_grid/strings.json b/custom_components/national_grid/strings.json
index 0b12e49..1986aad 100644
--- a/custom_components/national_grid/strings.json
+++ b/custom_components/national_grid/strings.json
@@ -36,6 +36,7 @@
         },
         "abort": {
             "already_configured": "This account is already configured.",
+            "no_accounts_found": "Login succeeded but no National Grid accounts were found on this profile.",
             "reauth_successful": "Re-authentication successful.",
             "reconfigure_successful": "Account selection updated successfully."
         }
diff --git a/custom_components/national_grid/translations/en.json b/custom_components/national_grid/translations/en.json
index 0b12e49..1986aad 100644
--- a/custom_components/national_grid/translations/en.json
+++ b/custom_components/national_grid/translations/en.json
@@ -36,6 +36,7 @@
         },
         "abort": {
             "already_configured": "This account is already configured.",
+            "no_accounts_found": "Login succeeded but no National Grid accounts were found on this profile.",
             "reauth_successful": "Re-authentication successful.",
             "reconfigure_successful": "Account selection updated successfully."
         }
diff --git a/tests/test_config_flow.py b/tests/test_config_flow.py
index fe54132..ff828c5 100644
--- a/tests/test_config_flow.py
+++ b/tests/test_config_flow.py
@@ -528,6 +528,43 @@ async def test_reconfigure_unknown_error(hass: HomeAssistant) -> None:
     assert result["errors"]["base"] == "unknown"
 
 
+async def test_user_step_no_accounts_found(hass: HomeAssistant) -> None:
+    """Test user step aborts when login succeeds but no accounts are returned."""
+    with patch(PATCH_CLIENT) as mock_cls:
+        client = mock_cls.return_value
+        client.__aenter__ = AsyncMock(return_value=client)
+        client.__aexit__ = AsyncMock(return_value=False)
+        client.get_linked_accounts = AsyncMock(return_value=[])
+
+        result = await hass.config_entries.flow.async_init(
+            DOMAIN,
+            context={"source": config_entries.SOURCE_USER},
+            data={
+                CONF_USERNAME: MOCK_USERNAME,
+                CONF_PASSWORD: MOCK_PASSWORD,
+            },
+        )
+
+    assert result["type"] is FlowResultType.ABORT
+    assert result["reason"] == "no_accounts_found"
+
+
+async def test_reconfigure_no_accounts_found(hass: HomeAssistant) -> None:
+    """Test reconfigure aborts when login succeeds but no accounts are returned."""
+    entry = _make_reconfigure_entry(hass)
+
+    with patch(PATCH_CLIENT) as mock_cls:
+        client = mock_cls.return_value
+        client.__aenter__ = AsyncMock(return_value=client)
+        client.__aexit__ = AsyncMock(return_value=False)
+        client.get_linked_accounts = AsyncMock(return_value=[])
+
+        result = await entry.start_reconfigure_flow(hass)
+
+    assert result["type"] is FlowResultType.ABORT
+    assert result["reason"] == "no_accounts_found"
+
+
 async def test_already_configured(hass: HomeAssistant) -> None:
     """Test that duplicate unique_id aborts."""
     entry = MockConfigEntry(