diff --git a/backend/internal/handler/auth_handler.go b/backend/internal/handler/auth_handler.go
index a9af910d..592a0d82 100644
--- a/backend/internal/handler/auth_handler.go
+++ b/backend/internal/handler/auth_handler.go
@@ -203,7 +203,7 @@ func (h *AuthHandler) SendVerifyCode(c *gin.Context) {
 		return
 	}
 
-	result, err := h.authService.SendVerifyCodeAsync(c.Request.Context(), req.Email)
+	result, err := h.authService.SendVerifyCodeAsync(c.Request.Context(), req.Email, c.GetHeader("Accept-Language"))
 	if err != nil {
 		response.ErrorFrom(c, err)
 		return
@@ -602,7 +602,7 @@ func (h *AuthHandler) ForgotPassword(c *gin.Context) {
 
 	// Request password reset (async)
 	// Note: This returns success even if email doesn't exist (to prevent enumeration)
-	if err := h.authService.RequestPasswordResetAsync(c.Request.Context(), req.Email, frontendBaseURL); err != nil {
+	if err := h.authService.RequestPasswordResetAsync(c.Request.Context(), req.Email, frontendBaseURL, c.GetHeader("Accept-Language")); err != nil {
 		response.ErrorFrom(c, err)
 		return
 	}
diff --git a/backend/internal/handler/auth_oauth_pending_flow.go b/backend/internal/handler/auth_oauth_pending_flow.go
index 1014a3e8..550363fd 100644
--- a/backend/internal/handler/auth_oauth_pending_flow.go
+++ b/backend/internal/handler/auth_oauth_pending_flow.go
@@ -545,7 +545,7 @@ func (h *AuthHandler) SendPendingOAuthVerifyCode(c *gin.Context) {
 		return
 	}
 
-	result, err := h.authService.SendPendingOAuthVerifyCode(c.Request.Context(), req.Email)
+	result, err := h.authService.SendPendingOAuthVerifyCode(c.Request.Context(), req.Email, c.GetHeader("Accept-Language"))
 	if err != nil {
 		response.ErrorFrom(c, err)
 		return
diff --git a/backend/internal/handler/totp_handler.go b/backend/internal/handler/totp_handler.go
index 5c5eb567..f9151dab 100644
--- a/backend/internal/handler/totp_handler.go
+++ b/backend/internal/handler/totp_handler.go
@@ -172,7 +172,7 @@ func (h *TotpHandler) SendVerifyCode(c *gin.Context) {
 		return
 	}
 
-	if err := h.totpService.SendVerifyCode(c.Request.Context(), subject.UserID); err != nil {
+	if err := h.totpService.SendVerifyCode(c.Request.Context(), subject.UserID, c.GetHeader("Accept-Language")); err != nil {
 		response.ErrorFrom(c, err)
 		return
 	}
diff --git a/backend/internal/handler/user_handler.go b/backend/internal/handler/user_handler.go
index f1dbf4e1..95cb1482 100644
--- a/backend/internal/handler/user_handler.go
+++ b/backend/internal/handler/user_handler.go
@@ -335,7 +335,7 @@ func (h *UserHandler) SendEmailBindingCode(c *gin.Context) {
 		return
 	}
 
-	if err := h.authService.SendEmailIdentityBindCode(c.Request.Context(), subject.UserID, req.Email); err != nil {
+	if err := h.authService.SendEmailIdentityBindCode(c.Request.Context(), subject.UserID, req.Email, c.GetHeader("Accept-Language")); err != nil {
 		response.ErrorFrom(c, err)
 		return
 	}
@@ -363,7 +363,7 @@ func (h *UserHandler) SendNotifyEmailCode(c *gin.Context) {
 		return
 	}
 
-	err := h.userService.SendNotifyEmailCode(c.Request.Context(), subject.UserID, req.Email, h.emailService, h.emailCache)
+	err := h.userService.SendNotifyEmailCode(c.Request.Context(), subject.UserID, req.Email, h.emailService, h.emailCache, c.GetHeader("Accept-Language"))
 	if err != nil {
 		response.ErrorFrom(c, err)
 		return