diff --git a/backend/api_test.go b/backend/api_test.go
index 46d7151..3ba6b31 100644
--- a/backend/api_test.go
+++ b/backend/api_test.go
@@ -764,7 +764,6 @@ func TestAddAllowanceSimple(t *testing.T) {
 	createTestAllowance(e, "Test Allowance 1", 1000, 1)
 
 	request := map[string]interface{}{
-		"id":          1,
 		"amount":      10,
 		"description": "Added to allowance 1",
 	}
@@ -783,6 +782,30 @@ func TestAddAllowanceSimple(t *testing.T) {
 	history.Value(0).Object().Value("description").String().IsEqual("Added to allowance 1")
 }
 
+func TestAddAllowanceIdZero(t *testing.T) {
+	e := startServer(t)
+
+	createTestAllowance(e, "Test Allowance 1", 1000, 1)
+
+	request := map[string]interface{}{
+		"amount":      10,
+		"description": "Added to allowance 1",
+	}
+	e.POST("/user/1/allowance/0/add").WithJSON(request).Expect().Status(200)
+
+	// Verify the allowance is updated
+	allowances := e.GET("/user/1/allowance").Expect().Status(200).JSON().Array()
+	allowances.Value(0).Object().Value("id").Number().IsEqual(0)
+	allowances.Value(0).Object().Value("progress").Number().InDelta(10.0, 0.01)
+
+	// Verify the history is updated
+	history := e.GET("/user/1/history").Expect().Status(200).JSON().Array()
+	history.Length().IsEqual(1)
+	history.Value(0).Object().Value("allowance").Number().InDelta(10.0, 0.01)
+	history.Value(0).Object().Value("timestamp").String().AsDateTime().InRange(getDelta(time.Now(), 2.0))
+	history.Value(0).Object().Value("description").String().IsEqual("Added to allowance 1")
+}
+
 func TestAddAllowanceWithSpillage(t *testing.T) {
 	e := startServer(t)
 
@@ -791,7 +814,6 @@ func TestAddAllowanceWithSpillage(t *testing.T) {
 	e.PUT("/user/1/allowance/0").WithJSON(UpdateAllowanceRequest{Weight: 1}).Expect().Status(200)
 
 	request := map[string]interface{}{
-		"id":          1,
 		"amount":      10,
 		"description": "Added to allowance 1",
 	}
diff --git a/backend/db.go b/backend/db.go
index c6775c6..37d6fbb 100644
--- a/backend/db.go
+++ b/backend/db.go
@@ -561,36 +561,44 @@ func (db *Db) AddAllowanceAmount(userId int, allowanceId int, request AddAllowan
 		return err
 	}
 
-	// Fetch the target and progress of the specified allowance
-	var target, progress int
-	err = tx.Query("select target, balance from allowances where id = ? and user_id = ?").
-		Bind(allowanceId, userId).ScanSingle(&target, &progress)
-	if err != nil {
-		return err
-	}
-
-	// Calculate the amount to add to the current allowance
-	toAdd := remainingAmount
-	if progress+toAdd > target {
-		toAdd = target - progress
-	}
-	remainingAmount -= toAdd
-
-	// Update the current allowance
-	if toAdd > 0 {
-		err = tx.Query("update allowances set balance = balance + ? where id = ? and user_id = ?").
-			Bind(toAdd, allowanceId, userId).Exec()
+	if allowanceId == 0 {
+		err = tx.Query("update users set balance = balance + ? where id = ?").
+			Bind(remainingAmount, userId).Exec()
 		if err != nil {
 			return err
 		}
-	}
-
-	// If there's remaining amount, distribute it to the user's allowances
-	if remainingAmount > 0 {
-		err = db.addDistributedReward(tx, userId, remainingAmount)
+	} else {
+		// Fetch the target and progress of the specified allowance
+		var target, progress int
+		err = tx.Query("select target, balance from allowances where id = ? and user_id = ?").
+			Bind(allowanceId, userId).ScanSingle(&target, &progress)
 		if err != nil {
 			return err
 		}
+
+		// Calculate the amount to add to the current allowance
+		toAdd := remainingAmount
+		if progress+toAdd > target {
+			toAdd = target - progress
+		}
+		remainingAmount -= toAdd
+
+		// Update the current allowance
+		if toAdd > 0 {
+			err = tx.Query("update allowances set balance = balance + ? where id = ? and user_id = ?").
+				Bind(toAdd, allowanceId, userId).Exec()
+			if err != nil {
+				return err
+			}
+		}
+
+		// If there's remaining amount, distribute it to the user's allowances
+		if remainingAmount > 0 {
+			err = db.addDistributedReward(tx, userId, remainingAmount)
+			if err != nil {
+				return err
+			}
+		}
 	}
 
 	return tx.Commit()