diff --git a/src/db.py b/src/db.py
new file mode 100644
index 0000000..1b8118c
--- /dev/null
+++ b/src/db.py
@@ -0,0 +1,21 @@
+from pathlib import Path
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import DeclarativeBase, Session
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+def get_engine(db_path: Path | None = None):
+    if db_path is None:
+        db_path = Path.home() / ".spending_analysis" / "spending.db"
+        db_path.parent.mkdir(parents=True, exist_ok=True)
+    return create_engine(f"sqlite:///{db_path}")
+
+
+def get_session(db_path: Path | None = None) -> Session:
+    engine = get_engine(db_path)
+    Base.metadata.create_all(engine)
+    return Session(engine)
diff --git a/src/models/__init__.py b/src/models/__init__.py
index e69de29..52d7767 100644
--- a/src/models/__init__.py
+++ b/src/models/__init__.py
@@ -0,0 +1,6 @@
+from src.models.household import HouseholdMember
+from src.models.account import Account
+from src.models.category import Category
+from src.models.transaction import Transaction
+from src.models.rule import CategorizationRule
+from src.models.csv_mapping import CsvMapping
diff --git a/src/models/account.py b/src/models/account.py
new file mode 100644
index 0000000..71c29d6
--- /dev/null
+++ b/src/models/account.py
@@ -0,0 +1,24 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from sqlalchemy import ForeignKey, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from src.db import Base
+
+if TYPE_CHECKING:
+    from src.models.household import HouseholdMember
+
+
+class Account(Base):
+    __tablename__ = "accounts"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str] = mapped_column(String(100))
+    institution: Mapped[str] = mapped_column(String(100))
+    account_type: Mapped[str] = mapped_column(String(20))
+    owner_id: Mapped[int | None] = mapped_column(ForeignKey("household_members.id"))
+    is_shared: Mapped[bool] = mapped_column(default=False)
+
+    owner: Mapped[HouseholdMember | None] = relationship(back_populates="accounts")
diff --git a/src/models/category.py b/src/models/category.py
new file mode 100644
index 0000000..0083287
--- /dev/null
+++ b/src/models/category.py
@@ -0,0 +1,13 @@
+from sqlalchemy import String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from src.db import Base
+
+
+class Category(Base):
+    __tablename__ = "categories"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str] = mapped_column(String(100), unique=True)
+    default_tag: Mapped[str | None] = mapped_column(String(20))
+    icon: Mapped[str | None] = mapped_column(String(50))
diff --git a/src/models/csv_mapping.py b/src/models/csv_mapping.py
new file mode 100644
index 0000000..e0eef3b
--- /dev/null
+++ b/src/models/csv_mapping.py
@@ -0,0 +1,24 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from sqlalchemy import ForeignKey, String, Text
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from src.db import Base
+
+if TYPE_CHECKING:
+    from src.models.account import Account
+
+
+class CsvMapping(Base):
+    __tablename__ = "csv_mappings"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str] = mapped_column(String(100))
+    fingerprint: Mapped[str] = mapped_column(String(500))
+    column_map: Mapped[str] = mapped_column(Text)
+    amount_logic: Mapped[str] = mapped_column(String(50))
+    account_id: Mapped[int] = mapped_column(ForeignKey("accounts.id"))
+
+    account: Mapped[Account] = relationship()
diff --git a/src/models/household.py b/src/models/household.py
new file mode 100644
index 0000000..da66a8b
--- /dev/null
+++ b/src/models/household.py
@@ -0,0 +1,21 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from sqlalchemy import String
+from sqlalchemy.orm import Mapped, mapped_column, relationship as sa_relationship
+
+from src.db import Base
+
+if TYPE_CHECKING:
+    from src.models.account import Account
+
+
+class HouseholdMember(Base):
+    __tablename__ = "household_members"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str] = mapped_column(String(100))
+    relationship: Mapped[str] = mapped_column(String(50))
+
+    accounts: Mapped[list[Account]] = sa_relationship(back_populates="owner")
diff --git a/src/models/rule.py b/src/models/rule.py
new file mode 100644
index 0000000..fe9db1d
--- /dev/null
+++ b/src/models/rule.py
@@ -0,0 +1,26 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from sqlalchemy import ForeignKey, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from src.db import Base
+
+if TYPE_CHECKING:
+    from src.models.category import Category
+    from src.models.household import HouseholdMember
+
+
+class CategorizationRule(Base):
+    __tablename__ = "categorization_rules"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    pattern: Mapped[str] = mapped_column(String(300))
+    category_id: Mapped[int] = mapped_column(ForeignKey("categories.id"))
+    tag_override: Mapped[str | None] = mapped_column(String(20))
+    attributed_to_id: Mapped[int | None] = mapped_column(ForeignKey("household_members.id"))
+    priority: Mapped[int] = mapped_column(default=0)
+
+    category: Mapped[Category] = relationship()
+    attributed_to: Mapped[HouseholdMember | None] = relationship()
diff --git a/src/models/transaction.py b/src/models/transaction.py
new file mode 100644
index 0000000..83c8dd1
--- /dev/null
+++ b/src/models/transaction.py
@@ -0,0 +1,35 @@
+from __future__ import annotations
+
+import datetime
+from typing import TYPE_CHECKING
+
+from sqlalchemy import Date, ForeignKey, Numeric, String, Text
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from src.db import Base
+
+if TYPE_CHECKING:
+    from src.models.account import Account
+    from src.models.category import Category
+    from src.models.household import HouseholdMember
+
+
+class Transaction(Base):
+    __tablename__ = "transactions"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    date: Mapped[datetime.date] = mapped_column(Date)
+    amount: Mapped[float] = mapped_column(Numeric(10, 2))
+    description: Mapped[str] = mapped_column(String(300))
+    raw_description: Mapped[str | None] = mapped_column(Text)
+    account_id: Mapped[int] = mapped_column(ForeignKey("accounts.id"))
+    category_id: Mapped[int | None] = mapped_column(ForeignKey("categories.id"))
+    attributed_to_id: Mapped[int | None] = mapped_column(ForeignKey("household_members.id"))
+    tag: Mapped[str | None] = mapped_column(String(20))
+    source_category: Mapped[str | None] = mapped_column(String(100))
+    is_transfer: Mapped[bool] = mapped_column(default=False)
+    transfer_pair_id: Mapped[int | None] = mapped_column(ForeignKey("transactions.id"))
+
+    account: Mapped[Account] = relationship()
+    category: Mapped[Category | None] = relationship()
+    attributed_to: Mapped[HouseholdMember | None] = relationship()
diff --git a/tests/models/test_models.py b/tests/models/test_models.py
new file mode 100644
index 0000000..fc7c910
--- /dev/null
+++ b/tests/models/test_models.py
@@ -0,0 +1,112 @@
+import datetime
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import Session
+
+from src.db import Base
+from src.models.household import HouseholdMember
+from src.models.account import Account
+from src.models.category import Category
+from src.models.transaction import Transaction
+from src.models.rule import CategorizationRule
+from src.models.csv_mapping import CsvMapping
+
+
+def make_session():
+    engine = create_engine("sqlite:///:memory:")
+    Base.metadata.create_all(engine)
+    return Session(engine)
+
+
+def test_create_household_member():
+    session = make_session()
+    member = HouseholdMember(name="Andrew", relationship="self")
+    session.add(member)
+    session.commit()
+    assert member.id is not None
+    assert member.name == "Andrew"
+
+
+def test_create_account_with_owner():
+    session = make_session()
+    member = HouseholdMember(name="Andrew", relationship="self")
+    session.add(member)
+    session.flush()
+    account = Account(
+        name="Chase Freedom",
+        institution="Chase",
+        account_type="credit",
+        owner_id=member.id,
+    )
+    session.add(account)
+    session.commit()
+    assert account.owner.name == "Andrew"
+
+
+def test_create_category():
+    session = make_session()
+    cat = Category(name="Groceries", default_tag="needs")
+    session.add(cat)
+    session.commit()
+    assert cat.id is not None
+
+
+def test_create_transaction():
+    session = make_session()
+    member = HouseholdMember(name="Andrew", relationship="self")
+    session.add(member)
+    session.flush()
+    account = Account(name="Checking", institution="Wells Fargo", account_type="checking", owner_id=member.id)
+    cat = Category(name="Groceries", default_tag="needs")
+    session.add_all([account, cat])
+    session.flush()
+    txn = Transaction(
+        date=datetime.date(2026, 1, 15),
+        amount=-48.52,
+        description="WAL-MART #7181",
+        raw_description="PURCHASE AUTHORIZED ON 01/14 WAL-MART #7181 BEAUFORT SC CARD 5360",
+        account_id=account.id,
+        category_id=cat.id,
+        attributed_to_id=member.id,
+        tag="needs",
+    )
+    session.add(txn)
+    session.commit()
+    assert txn.id is not None
+    assert txn.account.name == "Checking"
+    assert txn.category.name == "Groceries"
+
+
+def test_create_categorization_rule():
+    session = make_session()
+    cat = Category(name="Groceries", default_tag="needs")
+    session.add(cat)
+    session.flush()
+    rule = CategorizationRule(
+        pattern="WAL-MART",
+        category_id=cat.id,
+        priority=10,
+    )
+    session.add(rule)
+    session.commit()
+    assert rule.id is not None
+
+
+def test_create_csv_mapping():
+    session = make_session()
+    member = HouseholdMember(name="Andrew", relationship="self")
+    session.add(member)
+    session.flush()
+    account = Account(name="Chase", institution="Chase", account_type="credit", owner_id=member.id)
+    session.add(account)
+    session.flush()
+    mapping = CsvMapping(
+        name="Chase Credit Card",
+        fingerprint="Transaction Date,Post Date,Description,Category,Type,Amount,Memo",
+        column_map='{"date": "Transaction Date", "amount": "Amount", "description": "Description"}',
+        amount_logic="signed",
+        account_id=account.id,
+    )
+    session.add(mapping)
+    session.commit()
+    assert mapping.id is not None