diff --git a/database/sql/schema.sql b/database/sql/schema.sql
index 93e038a..c29cc15 100644
--- a/database/sql/schema.sql
+++ b/database/sql/schema.sql
@@ -167,6 +167,13 @@ CREATE TABLE IF NOT EXISTS `transaction_tags` (
   CONSTRAINT `fk_transaction_tags_transaction` FOREIGN KEY (`transaction_id`) REFERENCES `transactions` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
+-- Account Tags table (Many-to-Many)
+CREATE TABLE IF NOT EXISTS `account_tags` (
+  `account_id` bigint(20) unsigned NOT NULL,
+  `tag_id` bigint(20) unsigned NOT NULL,
+  PRIMARY KEY (`account_id`,`tag_id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
 -- Transaction Images table
 CREATE TABLE IF NOT EXISTS `transaction_images` (
   `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
@@ -553,6 +560,7 @@ CREATE TABLE IF NOT EXISTS `user_settings` (
   CONSTRAINT `fk_user_settings_default_expense` FOREIGN KEY (`default_expense_account_id`) REFERENCES `accounts` (`id`) ON DELETE SET NULL ON UPDATE CASCADE,
   CONSTRAINT `fk_user_settings_default_income` FOREIGN KEY (`default_income_account_id`) REFERENCES `accounts` (`id`) ON DELETE SET NULL ON UPDATE CASCADE
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
 -- Notifications table
 CREATE TABLE IF NOT EXISTS `notifications` (
   `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
diff --git a/internal/router/router.go b/internal/router/router.go
index f4fdaa8..90f00d5 100644
--- a/internal/router/router.go
+++ b/internal/router/router.go
@@ -70,7 +70,7 @@ func Setup(db *gorm.DB, yunAPIClient *service.YunAPIClient, cfg *config.Config)
 	categoryService := service.NewCategoryService(categoryRepo)
 	tagService := service.NewTagService(tagRepo)
 	classificationService := service.NewClassificationService(classificationRepo, categoryRepo)
-	transactionService := service.NewTransactionService(transactionRepo, accountRepo, categoryRepo, tagRepo, db)
+	transactionService := service.NewTransactionService(transactionRepo, accountRepo, categoryRepo, tagRepo, ledgerRepo, db)
 	imageService := service.NewImageService(transactionImageRepo, transactionRepo, db, cfg.ImageUploadDir)
 	recurringService := service.NewRecurringTransactionService(recurringRepo, transactionRepo, accountRepo, categoryRepo, allocationRuleRepo, allocationRecordRepo, piggyBankRepo, db)
 	exchangeRateService := service.NewExchangeRateService(exchangeRateRepo)
@@ -347,7 +347,7 @@ func SetupWithRedis(db *gorm.DB, yunAPIClient *service.YunAPIClient, redisClient
 	categoryService := service.NewCategoryService(categoryRepo)
 	tagService := service.NewTagService(tagRepo)
 	classificationService := service.NewClassificationService(classificationRepo, categoryRepo)
-	transactionService := service.NewTransactionService(transactionRepo, accountRepo, categoryRepo, tagRepo, db)
+	transactionService := service.NewTransactionService(transactionRepo, accountRepo, categoryRepo, tagRepo, ledgerRepo, db)
 	imageService := service.NewImageService(transactionImageRepo, transactionRepo, db, cfg.ImageUploadDir)
 	recurringService := service.NewRecurringTransactionService(recurringRepo, transactionRepo, accountRepo, categoryRepo, allocationRuleRepo, allocationRecordRepo, piggyBankRepo, db)
 	reportService := service.NewReportService(reportRepo, exchangeRateRepo)
diff --git a/internal/service/transaction_service.go b/internal/service/transaction_service.go
index b65a451..1656b74 100644
--- a/internal/service/transaction_service.go
+++ b/internal/service/transaction_service.go
@@ -39,6 +39,7 @@ type TransactionInput struct {
 	ImagePath       string                 `json:"image_path,omitempty"`
 	ToAccountID     *uint                  `json:"to_account_id,omitempty"`
 	TagIDs          []uint                 `json:"tag_ids,omitempty"`
+	LedgerID        *uint                  `json:"ledger_id,omitempty"`
 }
 
 // TransactionListInput represents the input for listing transactions
@@ -65,6 +66,7 @@ type TransactionService struct {
 	accountRepo  *repository.AccountRepository
 	categoryRepo *repository.CategoryRepository
 	tagRepo      *repository.TagRepository
+	ledgerRepo   *repository.LedgerRepository
 	db           *gorm.DB
 }
 
@@ -74,6 +76,7 @@ func NewTransactionService(
 	accountRepo *repository.AccountRepository,
 	categoryRepo *repository.CategoryRepository,
 	tagRepo *repository.TagRepository,
+	ledgerRepo *repository.LedgerRepository,
 	db *gorm.DB,
 ) *TransactionService {
 	return &TransactionService{
@@ -81,6 +84,7 @@ func NewTransactionService(
 		accountRepo:  accountRepo,
 		categoryRepo: categoryRepo,
 		tagRepo:      tagRepo,
+		ledgerRepo:   ledgerRepo,
 		db:           db,
 	}
 }
@@ -160,6 +164,23 @@ func (s *TransactionService) CreateTransaction(userID uint, input TransactionInp
 		return nil, err
 	}
 
+	// If LedgerID is not provided, use the default ledger
+	var ledgerID uint
+	if input.LedgerID == nil || *input.LedgerID == 0 {
+		defaultLedger, err := s.ledgerRepo.GetDefault(userID)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get default ledger: %w", err)
+		}
+		ledgerID = defaultLedger.ID
+	} else {
+		ledgerID = *input.LedgerID
+		// Verify ledger exists
+		_, err := s.ledgerRepo.GetByID(userID, ledgerID)
+		if err != nil {
+			return nil, fmt.Errorf("failed to verify ledger: %w", err)
+		}
+	}
+
 	// Execute within a database transaction
 	var transaction *models.Transaction
 	err := s.db.Transaction(func(tx *gorm.DB) error {
@@ -216,6 +237,7 @@ func (s *TransactionService) CreateTransaction(userID uint, input TransactionInp
 			Note:            input.Note,
 			ImagePath:       input.ImagePath,
 			ToAccountID:     input.ToAccountID,
+			LedgerID:        &ledgerID,
 		}
 
 		// Save transaction with tags
@@ -414,6 +436,14 @@ func (s *TransactionService) UpdateTransaction(userID, id uint, input Transactio
 		transaction.Note = input.Note
 		transaction.ImagePath = input.ImagePath
 		transaction.ToAccountID = input.ToAccountID
+		if input.LedgerID != nil && *input.LedgerID > 0 {
+			// Verify ledger exists
+			_, err := s.ledgerRepo.GetByID(userID, *input.LedgerID)
+			if err != nil {
+				return fmt.Errorf("failed to verify ledger: %w", err)
+			}
+			transaction.LedgerID = input.LedgerID
+		}
 
 		if err := txTransactionRepo.UpdateWithTags(transaction, input.TagIDs); err != nil {
 			return fmt.Errorf("failed to update transaction: %w", err)