diff --git a/7project/backend/alembic/versions/a60134ef6c4c_add_categories.py b/7project/backend/alembic/versions/a60134ef6c4c_add_categories.py
new file mode 100644
index 0000000..7c1e599
--- /dev/null
+++ b/7project/backend/alembic/versions/a60134ef6c4c_add_categories.py
@@ -0,0 +1,48 @@
+"""add categories
+
+Revision ID: a60134ef6c4c
+Revises: c5e9d6c59812
+Create Date: 2025-10-09 14:29:31.170347
+
+"""
+from typing import Sequence, Union
+
+import fastapi_users_db_sqlalchemy
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'a60134ef6c4c'
+down_revision: Union[str, Sequence[str], None] = 'c5e9d6c59812'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('categories',
+    sa.Column('id', sa.Integer(), autoincrement=True, nullable=False),
+    sa.Column('name', sa.String(length=100), nullable=False),
+    sa.Column('description', sa.String(length=255), nullable=True),
+    sa.Column('user_id', fastapi_users_db_sqlalchemy.generics.GUID(), nullable=False),
+    sa.ForeignKeyConstraint(['user_id'], ['user.id'], ),
+    sa.PrimaryKeyConstraint('id'),
+    sa.UniqueConstraint('name')
+    )
+    op.create_table('category_transaction',
+    sa.Column('id_category', sa.Integer(), nullable=True),
+    sa.Column('id_transaction', sa.Integer(), nullable=True),
+    sa.ForeignKeyConstraint(['id_category'], ['categories.id'], ),
+    sa.ForeignKeyConstraint(['id_transaction'], ['transaction.id'], )
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('category_transaction')
+    op.drop_table('categories')
+    # ### end Alembic commands ###
diff --git a/7project/backend/alembic/versions/c5e9d6c59812_user_transaction_relationship.py b/7project/backend/alembic/versions/c5e9d6c59812_user_transaction_relationship.py
new file mode 100644
index 0000000..b88a489
--- /dev/null
+++ b/7project/backend/alembic/versions/c5e9d6c59812_user_transaction_relationship.py
@@ -0,0 +1,41 @@
+"""User transaction relationship
+
+Revision ID: c5e9d6c59812
+Revises: 81f275275556
+Create Date: 2025-10-09 14:17:19.983889
+
+"""
+from typing import Sequence, Union
+
+import fastapi_users_db_sqlalchemy
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'c5e9d6c59812'
+down_revision: Union[str, Sequence[str], None] = '81f275275556'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.alter_column('transaction', 'user_id',
+               existing_type=sa.UUID(),
+               type_=fastapi_users_db_sqlalchemy.generics.GUID(),
+               existing_nullable=False)
+    op.create_foreign_key(None, 'transaction', 'user', ['user_id'], ['id'])
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_constraint(None, 'transaction', type_='foreignkey')
+    op.alter_column('transaction', 'user_id',
+               existing_type=fastapi_users_db_sqlalchemy.generics.GUID(),
+               type_=sa.UUID(),
+               existing_nullable=False)
+    # ### end Alembic commands ###
diff --git a/7project/backend/app/core/db.py b/7project/backend/app/core/db.py
index 40ff77f..9c8cad7 100644
--- a/7project/backend/app/core/db.py
+++ b/7project/backend/app/core/db.py
@@ -17,6 +17,7 @@ if not DATABASE_URL:
 # Load all models to register them
 from app.models.user import User
 from app.models.transaction import Transaction
+from app.models.categories import Category
 
 ssl_enabled = os.getenv("MARIADB_HOST", "localhost") != "localhost"
 connect_args = {"ssl": {"ssl": True}} if ssl_enabled else {}
diff --git a/7project/backend/app/models/categories.py b/7project/backend/app/models/categories.py
new file mode 100644
index 0000000..641ca2d
--- /dev/null
+++ b/7project/backend/app/models/categories.py
@@ -0,0 +1,22 @@
+from fastapi_users_db_sqlalchemy import GUID
+from sqlalchemy import Column, Integer, String, ForeignKey, Table
+from sqlalchemy.orm import relationship
+
+from app.core.base import Base
+
+association_table = Table(
+    "category_transaction",
+    Base.metadata,
+    Column("id_category", Integer, ForeignKey("categories.id")),
+    Column("id_transaction", Integer, ForeignKey("transaction.id"))
+)
+
+
+class Category(Base):
+    __tablename__ = "categories"
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    name = Column(String(length=100), unique=True, nullable=False)
+    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)
diff --git a/7project/backend/app/models/transaction.py b/7project/backend/app/models/transaction.py
index bc13565..39b640d 100644
--- a/7project/backend/app/models/transaction.py
+++ b/7project/backend/app/models/transaction.py
@@ -1,9 +1,15 @@
-from sqlalchemy import Column, Integer, String, Float
+from fastapi_users_db_sqlalchemy import GUID
+from sqlalchemy import Column, Integer, String, Float, ForeignKey, UUID
+from sqlalchemy.orm import relationship
 from app.core.base import Base
 
+
 class Transaction(Base):
     __tablename__ = "transaction"
     id = Column(Integer, primary_key=True, autoincrement=True)
     amount = Column(Float, nullable=False)
     description = Column(String(length=255), nullable=True)
+    user_id = Column(GUID, ForeignKey("user.id"), nullable=False)
 
+    # Relationship
+    user = relationship("User", back_populates="transactions")
diff --git a/7project/backend/app/models/user.py b/7project/backend/app/models/user.py
index 4c0f206..836dddf 100644
--- a/7project/backend/app/models/user.py
+++ b/7project/backend/app/models/user.py
@@ -1,7 +1,13 @@
 from sqlalchemy import Column, String
+from sqlalchemy.orm import relationship
 from fastapi_users.db import SQLAlchemyBaseUserTableUUID
 from app.core.base import Base
 
+
 class User(SQLAlchemyBaseUserTableUUID, Base):
     first_name = Column(String(length=100), nullable=True)
     last_name = Column(String(length=100), nullable=True)
+
+    # Relationship
+    transactions = relationship("Transaction", back_populates="user")
+    categories = relationship("Category", back_populates="user")
\ No newline at end of file
diff --git a/7project/create_migration.sh b/7project/create_migration.sh
index de43ffc..f8e8c04 100644
--- a/7project/create_migration.sh
+++ b/7project/create_migration.sh
@@ -8,4 +8,8 @@ fi
 cd backend || { echo "Directory 'backend' does not exist"; exit 1; }
 alembic revision --autogenerate -m "$1"
 git add alembic/versions/*
+YELLOW='\033[1;33m'
+NC='\033[0m' # No Color
+
+echo -e "${YELLOW}Don't forget to check imports in the new migration file!${NC}"
 cd - || exit
\ No newline at end of file