diff --git a/src/fiber_package/entity/person.py b/src/fiber_package/entity/person.py
index d71cd2c..f4685e7 100644
--- a/src/fiber_package/entity/person.py
+++ b/src/fiber_package/entity/person.py
@@ -1,5 +1,6 @@
-from pydantic import model_validator, EmailStr, Field
+from pydantic import model_validator, EmailStr, Field, computed_field
 from typing import Self, Literal
+from datetime import date
 
 from fiber_package.base import FiberBaseModel
 from .enums import Membership, LanguageOption
@@ -20,6 +21,20 @@ class PersonModel(FiberBaseModel):
     # TODO: phone number
     address: Address | None = None
 
+    date_of_birth: date | None = None
+
+
+    @computed_field
+    @property
+    def underage(self) -> bool:
+        if self.date_of_birth is None:
+            return False
+        age = ( today.year - self.date_of_birth.year
+                - ( (today.month, today.day) 
+                    < (self.date_of_birth.month, self.date_of_birth.day) ) 
+            )
+        return age < 18 
+
     @model_validator(mode="after")
     def generate_full_name(self) -> Self:
         full_name = self.first_name
@@ -28,4 +43,3 @@ class PersonModel(FiberBaseModel):
         full_name += " " + self.last_name
         self.full_name = full_name
         return self
-