diff --git a/.env.prod b/.env.prod
index 00cde05..86b2978 100644
--- a/.env.prod
+++ b/.env.prod
@@ -107,4 +107,13 @@ MAX_IMAGES_PER_TX=9
 ALIYUN_ACCESS_KEY_ID=
 ALIYUN_ACCESS_KEY_SECRET=
 ALIYUN_SIGN_NAME=
-ALIYUN_TEMPLATE_CODE=
\ No newline at end of file
+ALIYUN_TEMPLATE_CODE=
+
+# ============================================
+# SMTP 邮件配置 (发送通知邮件)
+# ============================================
+SMTP_HOST=smtp.qq.com
+SMTP_PORT=587
+SMTP_USER=
+SMTP_PASSWORD=
+SMTP_FROM=
\ No newline at end of file
diff --git a/internal/repository/budget_repository.go b/internal/repository/budget_repository.go
index ce3f8db..51e6477 100644
--- a/internal/repository/budget_repository.go
+++ b/internal/repository/budget_repository.go
@@ -144,11 +144,13 @@ func (r *BudgetRepository) GetSpentAmount(budget *models.Budget, startDate, endD
 
 	// Filter by category if specified
 	if budget.CategoryID != nil {
-		// Get sub-categories
-		var subCategoryIDs []uint
-		r.db.Model(&models.Category{}).Where("parent_id = ?", *budget.CategoryID).Pluck("id", &subCategoryIDs)
+		// Get all sub-categories recursively
+		subCategoryIDs, err := r.getAllSubCategoryIDs(*budget.CategoryID)
+		if err != nil {
+			return 0, fmt.Errorf("failed to get sub-categories: %w", err)
+		}
 
-		// Include the category itself and all its children
+		// Include the category itself and all its descendant children
 		categoryIDs := append(subCategoryIDs, *budget.CategoryID)
 		query = query.Where("category_id IN ?", categoryIDs)
 	}
@@ -165,6 +167,29 @@ func (r *BudgetRepository) GetSpentAmount(budget *models.Budget, startDate, endD
 	return totalSpent, nil
 }
 
+// getAllSubCategoryIDs helps to find all descendant category IDs
+func (r *BudgetRepository) getAllSubCategoryIDs(parentID uint) ([]uint, error) {
+	var allIDs []uint
+	var currentLevelIDs = []uint{parentID}
+
+	// Iteratively find children level by level
+	for len(currentLevelIDs) > 0 {
+		var nextLevelIDs []uint
+		if err := r.db.Model(&models.Category{}).Where("parent_id IN ?", currentLevelIDs).Pluck("id", &nextLevelIDs).Error; err != nil {
+			return nil, err
+		}
+
+		if len(nextLevelIDs) == 0 {
+			break
+		}
+
+		allIDs = append(allIDs, nextLevelIDs...)
+		currentLevelIDs = nextLevelIDs
+	}
+
+	return allIDs, nil
+}
+
 // ExistsByID checks if a budget with the given ID exists for a user
 func (r *BudgetRepository) ExistsByID(userID, id uint) (bool, error) {
 	var count int64