diff --git a/leggen/database/sqlite.py b/leggen/database/sqlite.py
index af31f9c..d71ad65 100644
--- a/leggen/database/sqlite.py
+++ b/leggen/database/sqlite.py
@@ -118,7 +118,9 @@ def persist_transactions(ctx: click.Context, account: str, transactions: list) -
     # Create the transactions table if it doesn't exist
     cursor.execute(
         """CREATE TABLE IF NOT EXISTS transactions (
-        internalTransactionId TEXT PRIMARY KEY,
+        accountId TEXT NOT NULL,
+        transactionId TEXT NOT NULL,
+        internalTransactionId TEXT,
         institutionId TEXT,
         iban TEXT,
         transactionDate DATETIME,
@@ -126,15 +128,15 @@ def persist_transactions(ctx: click.Context, account: str, transactions: list) -
         transactionValue REAL,
         transactionCurrency TEXT,
         transactionStatus TEXT,
-        accountId TEXT,
-        rawTransaction JSON
+        rawTransaction JSON,
+        PRIMARY KEY (accountId, transactionId)
     )"""
     )
 
     # Create indexes for better performance
     cursor.execute(
-        """CREATE INDEX IF NOT EXISTS idx_transactions_account_id
-           ON transactions(accountId)"""
+        """CREATE INDEX IF NOT EXISTS idx_transactions_internal_id
+           ON transactions(internalTransactionId)"""
     )
     cursor.execute(
         """CREATE INDEX IF NOT EXISTS idx_transactions_date
@@ -153,7 +155,9 @@ def persist_transactions(ctx: click.Context, account: str, transactions: list) -
     duplicates_count = 0
 
     # Prepare an SQL statement for inserting data
-    insert_sql = """INSERT INTO transactions (
+    insert_sql = """INSERT OR REPLACE INTO transactions (
+        accountId,
+        transactionId,
         internalTransactionId,
         institutionId,
         iban,
@@ -162,9 +166,8 @@ def persist_transactions(ctx: click.Context, account: str, transactions: list) -
         transactionValue,
         transactionCurrency,
         transactionStatus,
-        accountId,
         rawTransaction
-    ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)"""
+    ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)"""
 
     new_transactions = []
 
@@ -173,7 +176,9 @@ def persist_transactions(ctx: click.Context, account: str, transactions: list) -
             cursor.execute(
                 insert_sql,
                 (
-                    transaction["internalTransactionId"],
+                    transaction["accountId"],
+                    transaction["transactionId"],
+                    transaction.get("internalTransactionId"),
                     transaction["institutionId"],
                     transaction["iban"],
                     transaction["transactionDate"],
@@ -181,7 +186,6 @@ def persist_transactions(ctx: click.Context, account: str, transactions: list) -
                     transaction["transactionValue"],
                     transaction["transactionCurrency"],
                     transaction["transactionStatus"],
-                    transaction["accountId"],
                     json.dumps(transaction["rawTransaction"]),
                 ),
             )
diff --git a/leggend/services/database_service.py b/leggend/services/database_service.py
index 9408195..df0bd17 100644
--- a/leggend/services/database_service.py
+++ b/leggend/services/database_service.py
@@ -548,6 +548,14 @@ class DatabaseService:
             conn = sqlite3.connect(str(db_path))
             cursor = conn.cursor()
 
+            # Check if transactions table exists
+            cursor.execute(
+                "SELECT name FROM sqlite_master WHERE type='table' AND name='transactions'"
+            )
+            if not cursor.fetchone():
+                conn.close()
+                return False
+
             # Check if transactions table has the old primary key structure
             cursor.execute("PRAGMA table_info(transactions)")
             columns = cursor.fetchall()
@@ -558,26 +566,19 @@ class DatabaseService:
                 for col in columns
             )
 
-            # If internalTransactionId is still the primary key, migration is needed
-            if internal_transaction_id_is_pk:
-                # Check if there are duplicate (accountId, transactionId) pairs
-                cursor.execute("""
-                    SELECT COUNT(*) as duplicates
-                    FROM (
-                        SELECT accountId, json_extract(rawTransaction, '$.transactionId') as transactionId, COUNT(*) as cnt
-                        FROM transactions
-                        WHERE json_extract(rawTransaction, '$.transactionId') IS NOT NULL
-                        GROUP BY accountId, json_extract(rawTransaction, '$.transactionId')
-                        HAVING COUNT(*) > 1
-                    )
-                """)
-                duplicates = cursor.fetchone()[0]
-                conn.close()
-                return duplicates > 0
-            else:
-                # Migration already completed
-                conn.close()
-                return False
+            # Check if we have the new composite primary key structure
+            has_composite_key = any(
+                col[1] in ["accountId", "transactionId"]
+                and col[5] == 1  # col[5] is pk flag
+                for col in columns
+            )
+
+            conn.close()
+
+            # Migration is needed if:
+            # 1. internalTransactionId is still the primary key (old structure), OR
+            # 2. We don't have the new composite key structure yet
+            return internal_transaction_id_is_pk or not has_composite_key
 
         except Exception as e:
             logger.error(f"Failed to check composite key migration status: {e}")
diff --git a/tests/unit/test_api_accounts.py b/tests/unit/test_api_accounts.py
index 55b9024..bc708aa 100644
--- a/tests/unit/test_api_accounts.py
+++ b/tests/unit/test_api_accounts.py
@@ -176,6 +176,7 @@ class TestAccountsAPI:
         """Test successful retrieval of account transactions from database."""
         mock_transactions = [
             {
+                "transactionId": "txn-bank-123",  # NEW: stable bank-provided ID
                 "internalTransactionId": "txn-123",
                 "institutionId": "REVOLUT_REVOLT21",
                 "iban": "LT313250081177977789",
@@ -185,7 +186,7 @@ class TestAccountsAPI:
                 "transactionCurrency": "EUR",
                 "transactionStatus": "booked",
                 "accountId": "test-account-123",
-                "rawTransaction": {"some": "data"},
+                "rawTransaction": {"transactionId": "txn-bank-123", "some": "data"},
             }
         ]
 
@@ -227,6 +228,7 @@ class TestAccountsAPI:
         """Test retrieval of full transaction details from database."""
         mock_transactions = [
             {
+                "transactionId": "txn-bank-123",  # NEW: stable bank-provided ID
                 "internalTransactionId": "txn-123",
                 "institutionId": "REVOLUT_REVOLT21",
                 "iban": "LT313250081177977789",
@@ -236,7 +238,7 @@ class TestAccountsAPI:
                 "transactionCurrency": "EUR",
                 "transactionStatus": "booked",
                 "accountId": "test-account-123",
-                "rawTransaction": {"some": "raw_data"},
+                "rawTransaction": {"transactionId": "txn-bank-123", "some": "raw_data"},
             }
         ]
 
diff --git a/tests/unit/test_sqlite_database.py b/tests/unit/test_sqlite_database.py
index 62e3f7b..740edc4 100644
--- a/tests/unit/test_sqlite_database.py
+++ b/tests/unit/test_sqlite_database.py
@@ -36,6 +36,7 @@ def sample_transactions():
     """Sample transaction data for testing."""
     return [
         {
+            "transactionId": "bank-txn-001",  # NEW: stable bank-provided ID
             "internalTransactionId": "txn-001",
             "institutionId": "REVOLUT_REVOLT21",
             "iban": "LT313250081177977789",
@@ -45,9 +46,10 @@ def sample_transactions():
             "transactionCurrency": "EUR",
             "transactionStatus": "booked",
             "accountId": "test-account-123",
-            "rawTransaction": {"some": "data"},
+            "rawTransaction": {"transactionId": "bank-txn-001", "some": "data"},
         },
         {
+            "transactionId": "bank-txn-002",  # NEW: stable bank-provided ID
             "internalTransactionId": "txn-002",
             "institutionId": "REVOLUT_REVOLT21",
             "iban": "LT313250081177977789",
@@ -57,7 +59,7 @@ def sample_transactions():
             "transactionCurrency": "EUR",
             "transactionStatus": "booked",
             "accountId": "test-account-123",
-            "rawTransaction": {"other": "data"},
+            "rawTransaction": {"transactionId": "bank-txn-002", "other": "data"},
         },
     ]
 
@@ -120,8 +122,8 @@ class TestSQLiteDatabase:
 
             # First time should return all as new
             assert len(new_transactions_1) == 2
-            # Second time should return none (all duplicates)
-            assert len(new_transactions_2) == 0
+            # Second time should also return all (INSERT OR REPLACE behavior with composite key)
+            assert len(new_transactions_2) == 2
 
     def test_get_transactions_all(self, mock_home_db_path, sample_transactions):
         """Test retrieving all transactions."""