diff --git a/core/apps/orders/models/party.py b/core/apps/orders/models/party.py
index d3457e9..6fb7810 100644
--- a/core/apps/orders/models/party.py
+++ b/core/apps/orders/models/party.py
@@ -97,19 +97,19 @@ class PartyAmount(BaseModel):
     overdue_amount = models.BigIntegerField(default=0)
 
     def save(self, *args, **kwargs):
-        if self.calculated_amount > 0 and self.calculated_amount < self.paid_amount:
+        if self.calculated_amount > 0 and self.calculated_amount <= self.paid_amount:
             self.overdue_amount = self.paid_amount - self.calculated_amount
             self.payment_amount = 0
 
-        elif self.calculated_amount <= 0 and self.total_price < self.paid_amount:
+        elif self.calculated_amount <= 0 and self.total_price <= self.paid_amount:
             self.overdue_amount = self.paid_amount - self.total_price
             self.payment_amount = 0
 
-        elif self.calculated_amount > 0 and self.calculated_amount > self.paid_amount:
+        elif self.calculated_amount > 0 and self.calculated_amount >= self.paid_amount:
             self.payment_amount = self.calculated_amount - self.paid_amount
             self.overdue_amount = 0
         
-        elif self.calculated_amount <= 0 and self.total_price > self.paid_amount:
+        elif self.calculated_amount <= 0 and self.total_price >= self.paid_amount:
             self.payment_amount = self.total_price - self.paid_amount
             self.overdue_amount = 0
         else: