diff --git a/import2ledger/importers/_csv.py b/import2ledger/importers/_csv.py
index 325dcf5e0d97a42a4f1633463d61982c16cc94fd..3e5955b01e2e50e2e4c6700f7c43fd7e6839812b 100644
--- a/import2ledger/importers/_csv.py
+++ b/import2ledger/importers/_csv.py
@@ -43,9 +43,17 @@ class CSVImporterBase:
     Reader = csv.reader
     DictReader = csv.DictReader
 
+    @classmethod
+    def _row_rindex(cls, row, default=None):
+        """Return the index of the last cell in the row that has a value."""
+        for offset, value in enumerate(reversed(row), 1):
+            if value:
+                return len(row) - offset
+        return default
+
     @classmethod
     def _read_header_row(cls, row):
-        return {} if len(row) < cls._HEADER_MAX_LEN else None
+        return {} if cls._row_rindex(row, -1) + 1 < cls._HEADER_MAX_LEN else None
 
     @classmethod
     def _read_header(cls, input_file):