diff --git a/api/services/csv_parse.py b/api/services/csv_parse.py
index 555607d..04f9eff 100644
--- a/api/services/csv_parse.py
+++ b/api/services/csv_parse.py
@@ -157,6 +157,21 @@ def sanitize_columns(headers: list[str]) -> list[str]:
     return out
 
 
+def extra_cells(raw: list[str], width: int) -> list[str]:
+    """Non-empty cells beyond the header width (#82).
+
+    A row wider than its header would otherwise lose those values silently.
+    Empty trailing cells (a trailing comma, common in spreadsheet exports)
+    carry no data and are ignored.
+    """
+    return [c for c in raw[width:] if c.strip()]
+
+
+def ragged_row_reason(raw: list[str], width: int) -> str:
+    return (f"Row has {len(raw)} cells but the header has {width}; "
+            f"the extra value(s) would be lost, so the row was not imported.")
+
+
 def valid_identifier(name: str) -> bool:
     return bool(_IDENT_RE.match(name))
 
diff --git a/api/services/dynamic_loader.py b/api/services/dynamic_loader.py
index 2949f68..5f70390 100644
--- a/api/services/dynamic_loader.py
+++ b/api/services/dynamic_loader.py
@@ -22,7 +22,9 @@
 from api.services.csv_parse import (
     ALLOWED_TYPES,
     cast_value,
+    extra_cells,
     parse_csv,
+    ragged_row_reason,
     sanitize_columns,
     valid_identifier,
 )
@@ -273,6 +275,13 @@ def _do_upload(
                 values: list = []
                 raw_joined: list[str] = []
                 failed = False
+                extra = extra_cells(raw, len(columns))
+                if extra:
+                    if len(row_errors) < settings.MAX_ROW_ERRORS_REPORTED:
+                        row_errors.append({"rowNumber": row_number, "column": "(beyond header)",
+                                           "value": extra[0], "reason": ragged_row_reason(raw, len(columns))})
+                    failed_row_count += 1
+                    continue
                 for c in range(len(columns)):
                     cell = raw[c] if c < len(raw) else ""
                     raw_joined.append(cell)
diff --git a/api/services/te_loader.py b/api/services/te_loader.py
index 8c500dc..4e36195 100644
--- a/api/services/te_loader.py
+++ b/api/services/te_loader.py
@@ -30,8 +30,10 @@
 from api.db import Conn
 from api.services.csv_parse import (
     cast_value,
+    extra_cells,
     parse_csv,
     pg_type_to_allowed_type,
+    ragged_row_reason,
     sanitize_columns,
 )
 
@@ -218,6 +220,11 @@ def _err(row_number: int, column: str, value: str, reason: str) -> None:
                 row_number = r + 1
                 values: list = []
                 failed = False
+                extra = extra_cells(raw, len(columns))
+                if extra:
+                    _err(row_number, "(beyond header)", extra[0], ragged_row_reason(raw, len(columns)))
+                    failed_row_count += 1
+                    continue
                 for c, col_type in enumerate(col_types):
                     cell = raw[c].strip() if c < len(raw) else ""
                     if cell == "":
diff --git a/tests/test_ragged_rows.py b/tests/test_ragged_rows.py
new file mode 100644
index 0000000..db5bd4b
--- /dev/null
+++ b/tests/test_ragged_rows.py
@@ -0,0 +1,70 @@
+"""Rows wider than the header are reported, never silently truncated (#82)."""
+
+from __future__ import annotations
+
+import os
+import unittest
+import uuid
+
+import pytest
+from fastapi.testclient import TestClient
+
+from api.main import app
+from api.services.csv_parse import extra_cells
+
+_HELP = ("Start PostgreSQL and ensure api/ can reach it (PGHOST/PGPORT/PGUSER/"
+         "PGPASSWORD/PGDATABASE). See scripts/start-api.ps1.")
+
+
+@pytest.mark.unit
+class ExtraCells(unittest.TestCase):
+    def test_non_empty_cells_beyond_the_header_are_returned(self):
+        self.assertEqual(extra_cells(["1", "2", "x", ""], 2), ["x"])
+
+    def test_trailing_empty_cells_are_not_extra(self):
+        self.assertEqual(extra_cells(["1", "2", "", "  "], 2), [])
+
+    def test_short_rows_have_no_extra_cells(self):
+        self.assertEqual(extra_cells(["1"], 2), [])
+
+
+@pytest.mark.integration
+class RaggedRowsOverTheApi(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.ctx = TestClient(app)
+        try:
+            cls.client = cls.ctx.__enter__()
+        except Exception as exc:  # noqa: BLE001
+            raise AssertionError(f"Could not start the API: {type(exc).__name__}: {exc}\n{_HELP}") from None
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.ctx.__exit__(None, None, None)
+
+    def setUp(self):
+        self.tag = f"{os.getpid()}_{uuid.uuid4().hex[:8]}"
+
+    def _upload(self, content: str, **extra) -> dict:
+        body = {"fileName": f"ragged_{self.tag}.csv", "content": content, **extra}
+        return self.client.post("/api/csv/upload", json=body).json()
+
+    def test_dynamic_mode_reports_a_row_wider_than_the_header(self):
+        res = self._upload(f"a,b\n1,{self.tag}\n2,{self.tag},LOST\n")
+        self.assertEqual(res["status"], "ok")
+        self.assertEqual((res["insertedRows"], res["failedRows"]), (1, 1))
+        err = res["rowErrors"][0]
+        self.assertEqual((err["rowNumber"], err["value"]), (2, "LOST"))
+        self.assertIn("header has 2", err["reason"])
+
+    def test_dynamic_mode_accepts_a_trailing_empty_cell(self):
+        res = self._upload(f"a,b\n1,{self.tag},\n")
+        self.assertEqual((res["status"], res["insertedRows"], res["failedRows"]), ("ok", 1, 0))
+
+    def test_te_mode_reports_a_row_wider_than_the_header(self):
+        content = (f"name,org_type,country\nRAG_{self.tag}_1,government,AU\n"
+                   f"RAG_{self.tag}_2,government,AU,LOST\n")
+        res = self._upload(content, mode="te", targetTable="organisations")
+        self.assertEqual(res["status"], "ok")
+        self.assertEqual((res["insertedRows"], res["failedRows"]), (1, 1))
+        self.assertEqual(res["rowErrors"][0]["value"], "LOST")