diff --git a/eu_einvoice/european_e_invoice/doctype/e_invoice_import/e_invoice_import.json b/eu_einvoice/european_e_invoice/doctype/e_invoice_import/e_invoice_import.json
index 889a12b..d2bab50 100644
--- a/eu_einvoice/european_e_invoice/doctype/e_invoice_import/e_invoice_import.json
+++ b/eu_einvoice/european_e_invoice/doctype/e_invoice_import/e_invoice_import.json
@@ -21,6 +21,7 @@
   "amended_from",
   "agreement_tab",
   "seller_section",
+  "seller_id",
   "seller_name",
   "seller_tax_id",
   "seller_address_line_1",
@@ -35,6 +36,7 @@
   "create_supplier_address",
   "buyer_section",
   "column_break_reul",
+  "buyer_id",
   "buyer_name",
   "buyer_address_line_1",
   "buyer_address_line_2",
@@ -467,6 +469,18 @@
    "fieldtype": "Text",
    "label": "Validation Warnings",
    "read_only": 1
+  },
+  {
+   "fieldname": "buyer_id",
+   "fieldtype": "Data",
+   "label": "Buyer ID",
+   "read_only": 1
+  },
+  {
+   "fieldname": "seller_id",
+   "fieldtype": "Data",
+   "label": "Seller ID",
+   "read_only": 1
   }
  ],
  "index_web_pages_for_search": 1,
@@ -477,7 +491,7 @@
    "link_fieldname": "e_invoice_import"
   }
  ],
- "modified": "2025-05-07 00:53:28.840615",
+ "modified": "2025-10-01 02:52:45.579946",
  "modified_by": "Administrator",
  "module": "European e-Invoice",
  "name": "E Invoice Import",
diff --git a/eu_einvoice/european_e_invoice/doctype/e_invoice_import/e_invoice_import.py b/eu_einvoice/european_e_invoice/doctype/e_invoice_import/e_invoice_import.py
index f21283e..57ddcff 100644
--- a/eu_einvoice/european_e_invoice/doctype/e_invoice_import/e_invoice_import.py
+++ b/eu_einvoice/european_e_invoice/doctype/e_invoice_import/e_invoice_import.py
@@ -52,6 +52,7 @@ class EInvoiceImport(Document):
 		buyer_address_line_2: DF.Data | None
 		buyer_city: DF.Data | None
 		buyer_country: DF.Link | None
+		buyer_id: DF.Data | None
 		buyer_name: DF.Data | None
 		buyer_postcode: DF.Data | None
 		charge_total: DF.Currency
@@ -76,6 +77,7 @@ class EInvoiceImport(Document):
 		seller_address_line_2: DF.Data | None
 		seller_city: DF.Data | None
 		seller_country: DF.Link | None
+		seller_id: DF.Data | None
 		seller_name: DF.Data | None
 		seller_postcode: DF.Data | None
 		seller_tax_id: DF.Data | None
@@ -105,6 +107,7 @@ def before_save(self):
 			self.read_values_from_einvoice()
 			self.guess_supplier()
 			self.guess_company()
+			self.guess_company_and_supplier()
 			self.guess_uom()
 			self.guess_item_code()
 
@@ -221,6 +224,7 @@ def _validate_schematron(self, xml_bytes):
 
 	def parse_seller(self, seller: "TradeParty"):
 		self.seller_name = str(seller.name)
+		self.seller_id = str(seller.id)
 		self.seller_tax_id = (
 			seller.tax_registrations.children[0].id._text if seller.tax_registrations.children else None
 		)
@@ -228,6 +232,7 @@ def parse_seller(self, seller: "TradeParty"):
 
 	def parse_buyer(self, buyer: "TradeParty"):
 		self.buyer_name = str(buyer.name)
+		self.buyer_id = str(buyer.id)
 		self.parse_address(buyer.address, "buyer")
 
 	def parse_address(self, address: "PostalTradeAddress", prefix: str) -> _dict:
@@ -329,11 +334,19 @@ def guess_supplier(self):
 		if self.supplier:
 			return
 
-		if frappe.db.exists("Supplier", self.seller_name):
+		if self.seller_id and frappe.db.exists("Supplier", self.seller_id):
+			self.supplier = self.seller_id
+			return
+
+		if self.seller_name and frappe.db.exists("Supplier", self.seller_name):
 			self.supplier = self.seller_name
+			return
 
-		if self.seller_tax_id:
-			self.supplier = frappe.db.get_value("Supplier", {"tax_id": self.seller_tax_id}, "name")
+		if self.seller_tax_id and (
+			supplier := frappe.db.get_value("Supplier", {"tax_id": self.seller_tax_id}, "name")
+		):
+			self.supplier = supplier
+			return
 
 	def guess_company(self):
 		if self.company:
@@ -341,7 +354,37 @@ def guess_company(self):
 
 		if frappe.db.exists("Company", self.buyer_name):
 			self.company = self.buyer_name
-		else:
+
+	def guess_company_and_supplier(self):
+		"""Guess company and supplier based on buyer ID.
+
+		If the buyer ID is provided and we have already found either Company or
+		Supplier, we can find the other one.
+		"""
+		if not self.buyer_id:
+			return
+
+		if self.company and not self.supplier:
+			suppliers = frappe.get_all(
+				"Customer Number At Supplier",
+				filters={"customer_number": self.buyer_id, "company": self.company, "parenttype": "Supplier"},
+				pluck="parent",
+				limit=2,
+			)
+			if len(suppliers) == 1:
+				self.supplier = suppliers[0]
+
+		if self.supplier and not self.company:
+			companies = frappe.get_all(
+				"Customer Number At Supplier",
+				filters={"customer_number": self.buyer_id, "parent": self.supplier, "parenttype": "Supplier"},
+				pluck="company",
+				limit=2,
+			)
+			if len(companies) == 1:
+				self.company = companies[0]
+
+		if not self.company:
 			self.company = get_default_company()
 
 	def guess_uom(self):