diff --git a/sdk/api/handlers/handlers.go b/sdk/api/handlers/handlers.go
index d3359353..68859853 100644
--- a/sdk/api/handlers/handlers.go
+++ b/sdk/api/handlers/handlers.go
@@ -810,7 +810,7 @@ func (h *BaseAPIHandler) WriteErrorResponse(c *gin.Context, msg *interfaces.Erro
 	if msg != nil && msg.StatusCode > 0 {
 		status = msg.StatusCode
 	}
-	if msg != nil && msg.Addon != nil {
+	if msg != nil && msg.Addon != nil && PassthroughHeadersEnabled(h.Cfg) {
 		for key, values := range msg.Addon {
 			if len(values) == 0 {
 				continue
diff --git a/sdk/api/handlers/handlers_error_response_test.go b/sdk/api/handlers/handlers_error_response_test.go
new file mode 100644
index 00000000..cde4547f
--- /dev/null
+++ b/sdk/api/handlers/handlers_error_response_test.go
@@ -0,0 +1,68 @@
+package handlers
+
+import (
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"reflect"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/interfaces"
+	sdkconfig "github.com/router-for-me/CLIProxyAPI/v6/sdk/config"
+)
+
+func TestWriteErrorResponse_AddonHeadersDisabledByDefault(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	recorder := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(recorder)
+	c.Request = httptest.NewRequest(http.MethodGet, "/", nil)
+
+	handler := NewBaseAPIHandlers(nil, nil)
+	handler.WriteErrorResponse(c, &interfaces.ErrorMessage{
+		StatusCode: http.StatusTooManyRequests,
+		Error:      errors.New("rate limit"),
+		Addon: http.Header{
+			"Retry-After":  {"30"},
+			"X-Request-Id": {"req-1"},
+		},
+	})
+
+	if recorder.Code != http.StatusTooManyRequests {
+		t.Fatalf("status = %d, want %d", recorder.Code, http.StatusTooManyRequests)
+	}
+	if got := recorder.Header().Get("Retry-After"); got != "" {
+		t.Fatalf("Retry-After should be empty when passthrough is disabled, got %q", got)
+	}
+	if got := recorder.Header().Get("X-Request-Id"); got != "" {
+		t.Fatalf("X-Request-Id should be empty when passthrough is disabled, got %q", got)
+	}
+}
+
+func TestWriteErrorResponse_AddonHeadersEnabled(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	recorder := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(recorder)
+	c.Request = httptest.NewRequest(http.MethodGet, "/", nil)
+	c.Writer.Header().Set("X-Request-Id", "old-value")
+
+	handler := NewBaseAPIHandlers(&sdkconfig.SDKConfig{PassthroughHeaders: true}, nil)
+	handler.WriteErrorResponse(c, &interfaces.ErrorMessage{
+		StatusCode: http.StatusTooManyRequests,
+		Error:      errors.New("rate limit"),
+		Addon: http.Header{
+			"Retry-After":  {"30"},
+			"X-Request-Id": {"new-1", "new-2"},
+		},
+	})
+
+	if recorder.Code != http.StatusTooManyRequests {
+		t.Fatalf("status = %d, want %d", recorder.Code, http.StatusTooManyRequests)
+	}
+	if got := recorder.Header().Get("Retry-After"); got != "30" {
+		t.Fatalf("Retry-After = %q, want %q", got, "30")
+	}
+	if got := recorder.Header().Values("X-Request-Id"); !reflect.DeepEqual(got, []string{"new-1", "new-2"}) {
+		t.Fatalf("X-Request-Id = %#v, want %#v", got, []string{"new-1", "new-2"})
+	}
+}