diff --git a/account_statement_import_sheet_file_bg/models/account_statement_import.py b/account_statement_import_sheet_file_bg/models/account_statement_import.py
index e2b004bb..6ec72806 100644
--- a/account_statement_import_sheet_file_bg/models/account_statement_import.py
+++ b/account_statement_import_sheet_file_bg/models/account_statement_import.py
@@ -6,7 +6,7 @@
 from io import BytesIO
 
 from markupsafe import Markup
-from odoo import _, models
+from odoo import _, fields, models
 from openpyxl import Workbook, load_workbook
 
 
@@ -14,6 +14,8 @@ class AccountStatementImport(models.TransientModel):
     _name = "account.statement.import"
     _inherit = ["account.statement.import", "base.bg"]
 
+    csv_or_xls = fields.Selection([("csv", "CSV"), ("xls", "Excel")], string="File Type")
+
     def import_file_button(self, wizard_data=None):
         """Process the file chosen in the wizard, create a bank statement
         and return a link to its reconciliation page."""
@@ -37,9 +39,21 @@ def import_file_button(self, wizard_data=None):
 
                 if files:
                     for idx, file in enumerate(files):
+                        # Encode the file to string format, because background jobs cannot
+                        # be executed if the parameters passed are not serializable (the original format is bytes).
+                        # It is decoded back in import_file_button to be processed normally (line 99)
+                        if not isinstance(file, str):
+                            try:
+                                file_bytes = base64.b64decode(file)
+                                file_str = file_bytes.decode("utf-8")
+                                self.csv_or_xls = "csv"
+                            except Exception:
+                                file_str = base64.b64encode(file_bytes).decode("ascii")
+                                self.csv_or_xls = "xls"
+
                         # Create wizard data to be passed to bg job
                         wizard_data = {
-                            "statement_file": file,
+                            "statement_file": file_str,
                             "statement_filename": self.statement_filename,
                             "sheet_mapping_id": self.sheet_mapping_id.id,
                             "part_number": idx + 1,
@@ -86,6 +100,15 @@ def import_file_button(self, wizard_data=None):
                 # Extract part info before creating wizard
                 part_number = wizard_data.pop("part_number", None)
                 total_parts = wizard_data.pop("total_parts", None)
+                # Decode file from string back to bytes based on file type
+                statement_file = wizard_data.get("statement_file")
+                if statement_file and isinstance(statement_file, str):
+                    if self.csv_or_xls == "csv":
+                        # CSV files use UTF-8 encoding
+                        wizard_data["statement_file"] = base64.b64encode(statement_file.encode("utf-8"))
+                    elif self.csv_or_xls == "xls":
+                        # Excel files are already base64 encoded as ASCII strings
+                        wizard_data["statement_file"] = statement_file.encode("ascii")
                 wizard = self.create(wizard_data)
             else:
                 wizard = self