diff --git a/alembic/versions/20240619_1536_49a828f10b05_add_proof_currency_field.py b/alembic/versions/20240619_1536_49a828f10b05_add_proof_currency_field.py
new file mode 100644
index 00000000..b848bff1
--- /dev/null
+++ b/alembic/versions/20240619_1536_49a828f10b05_add_proof_currency_field.py
@@ -0,0 +1,43 @@
+"""Add Proof currency field
+
+Revision ID: 49a828f10b05
+Revises: 5f5835d81917
+Create Date: 2024-06-19 15:36:55.542647
+
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "49a828f10b05"
+down_revision: Union[str, None] = "5f5835d81917"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column("proofs", sa.Column("currency", sa.String(length=3), nullable=True))
+    # Set the currency to the currency of the first price for each proof
+    op.execute(
+        """
+        UPDATE proofs
+        SET currency = (
+            SELECT currency
+            FROM prices
+            WHERE prices.proof_id = proofs.id
+            LIMIT 1
+        )
+        WHERE type IN ('PRICE_TAG', 'RECEIPT')
+        """
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column("proofs", "currency")
+    # ### end Alembic commands ###
diff --git a/app/models.py b/app/models.py
index a3919724..65f4013d 100644
--- a/app/models.py
+++ b/app/models.py
@@ -124,7 +124,10 @@ class Proof(Base):
         Integer, nullable=False, server_default="0", index=True
     )
 
-    date = mapped_column(Date)
+    currency: Mapped[CurrencyEnum] = mapped_column(
+        ChoiceType(CurrencyEnum), nullable=True
+    )
+    date = mapped_column(Date, nullable=True)
 
     owner = mapped_column(String, index=True)
 
diff --git a/app/schemas.py b/app/schemas.py
index d029b354..90886897 100644
--- a/app/schemas.py
+++ b/app/schemas.py
@@ -185,6 +185,12 @@ class ProofFull(BaseModel):
     price_count: int = Field(
         description="number of prices for this proof.", examples=[15], default=0
     )
+    currency: CurrencyEnum | None = Field(
+        description="currency of the price, as a string. "
+        "The currency must be a valid currency code. "
+        "See https://en.wikipedia.org/wiki/ISO_4217 for a list of valid currency codes.",
+        examples=["EUR", "USD"],
+    )
     date: datetime.date | None = Field(
         description="date of the proof.", examples=["2024-01-01"]
     )
@@ -202,6 +208,7 @@ class ProofFull(BaseModel):
 
 class ProofBasicUpdatableFields(BaseModel):
     type: ProofTypeEnum | None = None
+    currency: CurrencyEnum | None = None
     date: datetime.date | None = None
 
     class Config:
@@ -491,6 +498,12 @@ class ProofFilter(Filter):
     price_count: Optional[int] | None = None
     price_count__gte: Optional[int] | None = None
     price_count__lte: Optional[int] | None = None
+    currency: Optional[str] | None = None
+    date: Optional[str] | None = None
+    date__gt: Optional[str] | None = None
+    date__gte: Optional[str] | None = None
+    date__lt: Optional[str] | None = None
+    date__lte: Optional[str] | None = None
 
     order_by: Optional[list[str]] | None = None
 
diff --git a/tests/integration/test_api.py b/tests/integration/test_api.py
index a99bcf10..6d59787e 100644
--- a/tests/integration/test_api.py
+++ b/tests/integration/test_api.py
@@ -912,6 +912,7 @@ def test_get_proofs(db_session, user_session: SessionModel, clean_proofs):
             "mimetype",
             "type",
             "price_count",
+            "currency",
             "date",
             "owner",
             "created",
@@ -1042,8 +1043,9 @@ def test_update_proof(
     )
     assert response.status_code == 200
     assert response.json()["type"] == "RECEIPT"
+    assert response.json()["currency"] is None
     assert response.json()["date"] is None
-    PROOF_UPDATE_PARTIAL = {"date": "2024-01-01"}
+    PROOF_UPDATE_PARTIAL = {"currency": "EUR", "date": "2024-01-01"}
     response = client.patch(
         f"/api/v1/proofs/{proof.id}",
         headers={"Authorization": f"Bearer {user_session.token}"},
@@ -1051,6 +1053,7 @@ def test_update_proof(
     )
     assert response.status_code == 200
     assert response.json()["type"] == "RECEIPT"
+    assert response.json()["currency"] == "EUR"
     assert response.json()["date"] == "2024-01-01"
 
     # with authentication and proof owner but extra fields