diff --git a/erpnext/controllers/taxes_and_totals.py b/erpnext/controllers/taxes_and_totals.py
index 239e47b15ac..bbf4ae36b61 100644
--- a/erpnext/controllers/taxes_and_totals.py
+++ b/erpnext/controllers/taxes_and_totals.py
@@ -12,6 +12,7 @@ from frappe.utils import cint, flt, round_based_on_smallest_currency_fraction
 import erpnext
 from erpnext.accounts.doctype.journal_entry.journal_entry import get_exchange_rate
 from erpnext.accounts.doctype.pricing_rule.utils import get_applied_pricing_rules
+from erpnext.accounts.utils import get_currency_precision
 from erpnext.controllers.accounts_controller import (
 	validate_conversion_rate,
 	validate_inclusive_tax,
@@ -707,7 +708,16 @@ class calculate_taxes_and_totals:
 					tax.item_wise_tax_detail = json.dumps(tax.item_wise_tax_detail)
 
 	def set_discount_amount(self):
-		if self.doc.additional_discount_percentage:
+		if self.doc.discount_amount:
+			self.doc.additional_discount_percentage = flt(
+				flt(
+					self.doc.discount_amount / flt(self.doc.get(scrub(self.doc.apply_discount_on))),
+					get_currency_precision(),
+				)
+				* 100,
+				self.doc.precision("additional_discount_percentage"),
+			)
+		elif self.doc.additional_discount_percentage:
 			self.doc.discount_amount = flt(
 				flt(self.doc.get(scrub(self.doc.apply_discount_on)))
 				* self.doc.additional_discount_percentage