diff --git a/pkg/internal/grpc/payment.go b/pkg/internal/grpc/payment.go
index 42040f4..f3c7811 100644
--- a/pkg/internal/grpc/payment.go
+++ b/pkg/internal/grpc/payment.go
@@ -2,11 +2,11 @@ package grpc
 
 import (
 	"context"
+
 	"git.solsynth.dev/hypernet/wallet/pkg/internal/database"
 	"git.solsynth.dev/hypernet/wallet/pkg/internal/models"
+	"git.solsynth.dev/hypernet/wallet/pkg/internal/services"
 	"git.solsynth.dev/hypernet/wallet/pkg/proto"
-	"github.com/samber/lo"
-	"github.com/shopspring/decimal"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 )
@@ -38,18 +38,20 @@ func (v *Server) MakeTransaction(ctx context.Context, request *proto.MakeTransac
 		return nil, status.Errorf(codes.InvalidArgument, "payer and payee cannot be both nil")
 	}
 
-	transaction := models.Transaction{
-		Amount: decimal.NewFromFloat(request.Amount),
-		Remark: request.Remark,
-	}
+	var payerWallet, payeeWallet *models.Wallet
 	if request.PayerId != nil {
-		transaction.PayerID = lo.ToPtr(uint(*request.PayerId))
+		if err := database.C.Where("id = ?", request.PayerId).First(&payerWallet); err != nil {
+			return nil, status.Errorf(codes.NotFound, "payer wallet not found: %v", err)
+		}
 	}
 	if request.PayeeId != nil {
-		transaction.PayeeID = lo.ToPtr(uint(*request.PayeeId))
+		if err := database.C.Where("id = ?", request.PayeeId).First(&payeeWallet); err != nil {
+			return nil, status.Errorf(codes.NotFound, "payee wallet not found: %v", err)
+		}
 	}
 
-	if err := database.C.Create(&transaction).Error; err != nil {
+	transaction, err := services.MakeTransaction(request.GetAmount(), request.GetRemark(), payerWallet, payeeWallet)
+	if err != nil {
 		return nil, status.Errorf(codes.Internal, err.Error())
 	}
 
@@ -61,30 +63,22 @@ func (v *Server) MakeTransactionWithAccount(ctx context.Context, request *proto.
 		return nil, status.Errorf(codes.InvalidArgument, "payer and payee cannot be both nil")
 	}
 
-	transaction := models.Transaction{
-		Amount: decimal.NewFromFloat(request.Amount),
-		Remark: request.Remark,
-	}
+	var payerWallet, payeeWallet *models.Wallet
 	if request.PayerAccountId != nil {
 		val := uint(*request.PayerAccountId)
-		var wallet models.Wallet
-		if err := database.C.Where("account_id = ?", val).First(&wallet).Error; err != nil {
-			return nil, status.Errorf(codes.NotFound, "payer wallet not found")
+		if err := database.C.Where("account_id = ?", val).First(&payerWallet).Error; err != nil {
+			return nil, status.Errorf(codes.NotFound, "payer wallet not found: %v", err)
 		}
-		transaction.Payer = &wallet
-		transaction.PayerID = &wallet.ID
 	}
 	if request.PayeeAccountId != nil {
 		val := uint(*request.PayeeAccountId)
-		var wallet models.Wallet
-		if err := database.C.Where("account_id = ?", val).First(&wallet).Error; err != nil {
-			return nil, status.Errorf(codes.NotFound, "payee wallet not found")
+		if err := database.C.Where("account_id = ?", val).First(&payeeWallet).Error; err != nil {
+			return nil, status.Errorf(codes.NotFound, "payee wallet not found: %v", err)
 		}
-		transaction.Payee = &wallet
-		transaction.PayeeID = &wallet.ID
 	}
 
-	if err := database.C.Create(&transaction).Error; err != nil {
+	transaction, err := services.MakeTransaction(request.GetAmount(), request.GetRemark(), payerWallet, payeeWallet)
+	if err != nil {
 		return nil, status.Errorf(codes.Internal, err.Error())
 	}
 
diff --git a/pkg/internal/services/payment.go b/pkg/internal/services/payment.go
new file mode 100644
index 0000000..697cda0
--- /dev/null
+++ b/pkg/internal/services/payment.go
@@ -0,0 +1,50 @@
+package services
+
+import (
+	"fmt"
+
+	"git.solsynth.dev/hypernet/wallet/pkg/internal/database"
+	"git.solsynth.dev/hypernet/wallet/pkg/internal/models"
+	"github.com/shopspring/decimal"
+)
+
+func MakeTransaction(amount float64, remark string, payer, payee *models.Wallet) (models.Transaction, error) {
+	transaction := models.Transaction{
+		Amount: decimal.NewFromFloat(amount),
+		Remark: remark,
+	}
+	if payer != nil {
+		transaction.PayerID = &payer.ID
+	}
+	if payee != nil {
+		transaction.PayeeID = &payee.ID
+	}
+
+	tx := database.C.Begin()
+
+	if err := tx.Create(&transaction).Error; err != nil {
+		tx.Rollback()
+		return transaction, err
+	}
+
+	if payer != nil {
+		payer.Balance = payer.Balance.Sub(transaction.Amount)
+		if err := tx.Model(payer).
+			Updates(&models.Wallet{Balance: payer.Balance}).Error; err != nil {
+			tx.Rollback()
+			return transaction, fmt.Errorf("failed to update payer wallet balance: %w", err)
+		}
+	}
+	if payee != nil {
+		payee.Balance = payee.Balance.Add(transaction.Amount)
+		if err := tx.Model(payee).
+			Updates(&models.Wallet{Balance: payee.Balance}).Error; err != nil {
+			tx.Rollback()
+			return transaction, fmt.Errorf("failed to update payee wallet balance: %w", err)
+		}
+	}
+
+	tx.Commit()
+
+	return transaction, nil
+}