diff --git a/l10n_it_intrastat_statement/models/intrastat_statement_purchase_section.py b/l10n_it_intrastat_statement/models/intrastat_statement_purchase_section.py
index cf21a693c5b3..05c66c294aee 100644
--- a/l10n_it_intrastat_statement/models/intrastat_statement_purchase_section.py
+++ b/l10n_it_intrastat_statement/models/intrastat_statement_purchase_section.py
@@ -148,10 +148,13 @@ def _prepare_statement_line(self, inv_intra_line, statement_id=None):
             statement_id.company_id or company_id,
             dp_model.precision_get('Account'))
 
+        # check if additional_units has a value
+        has_additional_units = bool(inv_intra_line.additional_units)
         res.update({
             'transaction_nature_id': transaction_nature_id.id,
             'weight_kg': round(inv_intra_line.weight_kg) or 1,
-            'additional_units': round(inv_intra_line.additional_units) or 1,
+            'additional_units': round(inv_intra_line.additional_units) or (
+                0 if not has_additional_units else 1),
             'statistic_amount_euro': statistic_amount,
             'delivery_code_id': delivery_code_id.id,
             'transport_code_id': transport_code_id.id,
diff --git a/l10n_it_intrastat_statement/models/intrastat_statement_sale_section.py b/l10n_it_intrastat_statement/models/intrastat_statement_sale_section.py
index 6fc2eec9a7af..0eab98d39987 100644
--- a/l10n_it_intrastat_statement/models/intrastat_statement_sale_section.py
+++ b/l10n_it_intrastat_statement/models/intrastat_statement_sale_section.py
@@ -112,10 +112,13 @@ def _prepare_statement_line(self, inv_intra_line, statement_id=None):
             statement_id.company_id or company_id,
             dp_model.precision_get('Account'))
 
+        # check if additional_units has a value
+        has_additional_units = bool(inv_intra_line.additional_units)
         res.update({
             'transaction_nature_id': transaction_nature_id.id,
             'weight_kg': round(inv_intra_line.weight_kg) or 1,
-            'additional_units': round(inv_intra_line.additional_units) or 1,
+            'additional_units': round(inv_intra_line.additional_units) or (
+                0 if not has_additional_units else 1),
             'statistic_amount_euro': statistic_amount,
             'delivery_code_id': delivery_code_id.id,
             'transport_code_id': transport_code_id.id,