diff --git a/backend/internal/service/ratelimit_service.go b/backend/internal/service/ratelimit_service.go
index 4f5b57cc..4d8009b7 100644
--- a/backend/internal/service/ratelimit_service.go
+++ b/backend/internal/service/ratelimit_service.go
@@ -142,11 +142,16 @@ func (s *RateLimitService) HandleUpstreamError(ctx context.Context, account *Acc
 
 	switch statusCode {
 	case 400:
-		// 只有当错误信息包含 "organization has been disabled" 时才禁用
+		// "organization has been disabled" → 永久禁用
 		if strings.Contains(strings.ToLower(upstreamMsg), "organization has been disabled") {
 			msg := "Organization disabled (400): " + upstreamMsg
 			s.handleAuthError(ctx, account, msg)
 			shouldDisable = true
+		} else if account.Platform == PlatformAnthropic && strings.Contains(strings.ToLower(upstreamMsg), "credit balance") {
+			// Anthropic API key 余额不足（语义等同 402），停止调度
+			msg := "Credit balance exhausted (400): " + upstreamMsg
+			s.handleAuthError(ctx, account, msg)
+			shouldDisable = true
 		}
 		// 其他 400 错误（如参数问题）不处理，不禁用账号
 	case 401: