diff --git a/employee/models.py b/employee/models.py
index 5dbb3f9..ca59e0c 100644
--- a/employee/models.py
+++ b/employee/models.py
@@ -16,6 +16,11 @@ class Employee(models.Model):
     perk_amount_per_month = models.DecimalField(max_digits=15, decimal_places=2)
     address = models.ForeignKey(Address, on_delete=models.CASCADE)
 
+    @property
+    def total_perk(self):
+        # calculation for the perk using transactions
+        return 0
+
     def __str__(self):
         return self.employee_id
 
diff --git a/expense/models.py b/expense/models.py
index 136f121..f5a6342 100644
--- a/expense/models.py
+++ b/expense/models.py
@@ -21,18 +21,24 @@ class Category(models.Model):
         return self.name
 
 
+class SubCategory(models.Model):
+    name = models.CharField(max_length=30)
+    parent_category = models.ForeignKey(Category, on_delete=models.CASCADE)
+
+    def __str__(self):
+        return self.name
+
+
 class Expense(models.Model):
-    PAYMENT_METHODS = (
-        ("RMB", "Reimburse"),
-        ("PER", "Perk")
-    )
     title = models.CharField(max_length=50)
-    category = models.ForeignKey(Category, on_delete=models.CASCADE)
+    sub_category = models.ForeignKey(SubCategory, on_delete=models.CASCADE)
     expense_id = models.CharField(max_length=15)
     date_of_creation = models.DateField()
     team_member = models.ForeignKey(Employee, on_delete=models.CASCADE)
     company_bank_account = models.ForeignKey(CompanyBankAccount, on_delete=models.CASCADE)
-    repayment_mode = models.CharField(max_length=10, choices=PAYMENT_METHODS, default=PAYMENT_METHODS[0][0])
+    is_reimbursement = models.BooleanField(default=False)
+    is_perk = models.BooleanField(default=False)
+    is_approved = models.BooleanField(default=False)
 
     @property
     def expense_total(self):