diff --git a/iyzipay/iyzipay_resource.py b/iyzipay/iyzipay_resource.py
index 200cd8b..674da69 100644
--- a/iyzipay/iyzipay_resource.py
+++ b/iyzipay/iyzipay_resource.py
@@ -144,6 +144,7 @@ def basket_pki(basket_items):
             pki_builder.append('itemType', item.get('itemType'))
             pki_builder.append('subMerchantKey', item.get('subMerchantKey'))
             pki_builder.append_price('subMerchantPrice', item.get('subMerchantPrice'))
+            pki_builder.append_price('withholdingTax', item.get('withholdingTax'))
             basket_items_pki.append(pki_builder.get_request_string())
         return basket_items_pki