diff --git a/7project/backend/app/models/categories.py b/7project/backend/app/models/categories.py
index 641ca2d..af7ef01 100644
--- a/7project/backend/app/models/categories.py
+++ b/7project/backend/app/models/categories.py
@@ -19,4 +19,4 @@ class Category(Base):
     description = Column(String(length=255), nullable=True)
     user_id = Column(GUID, ForeignKey("user.id"), nullable=False)
     user = relationship("User", back_populates="categories")
-    relationship(secondary=association_table)
+    relationship("Transaction", secondary=association_table, back_populates="categories")
diff --git a/7project/backend/app/models/transaction.py b/7project/backend/app/models/transaction.py
index 39b640d..6a7e0bf 100644
--- a/7project/backend/app/models/transaction.py
+++ b/7project/backend/app/models/transaction.py
@@ -1,7 +1,9 @@
+from exceptiongroup import catch
 from fastapi_users_db_sqlalchemy import GUID
-from sqlalchemy import Column, Integer, String, Float, ForeignKey, UUID
+from sqlalchemy import Column, Integer, String, Float, ForeignKey
 from sqlalchemy.orm import relationship
 from app.core.base import Base
+from app.models.categories import association_table
 
 
 class Transaction(Base):
@@ -13,3 +15,4 @@ class Transaction(Base):
 
     # Relationship
     user = relationship("User", back_populates="transactions")
+    categories = relationship("Category", secondary=association_table, back_populates="transactions")