diff --git a/src/main/java/it/gov/pagopa/idpay/transactions/service/RewardBatchServiceImpl.java b/src/main/java/it/gov/pagopa/idpay/transactions/service/RewardBatchServiceImpl.java
index 63b049c3..ca8f4578 100644
--- a/src/main/java/it/gov/pagopa/idpay/transactions/service/RewardBatchServiceImpl.java
+++ b/src/main/java/it/gov/pagopa/idpay/transactions/service/RewardBatchServiceImpl.java
@@ -922,7 +922,7 @@ private String mapTransactionToCsvRow(RewardTransaction trx, String initiativeId
 
         String invoiceNumber =
                 trx.getInvoiceData() != null && trx.getInvoiceData().getDocNumber() != null
-                        ? trx.getInvoiceData().getDocNumber()
+                        ? "=\"" + trx.getInvoiceData().getDocNumber() + "\""
                         : "";
 
         return String.join(";",