> ## Documentation Index > Fetch the complete documentation index at: https://docs.comfy.org/llms.txt > Use this file to discover all available pages before exploring further. # Concurrency Limits > Understand how concurrency limits control simultaneous Partner Node requests on your account. Concurrency limits control how many requests your account can process at the same time. Requests beyond your limit are rejected with a `429` error code. Your concurrency limit is determined by your credit purchase history, and applies at the platform level across all endpoints you call. ## How it works When you submit a request, the platform tracks it against your concurrency limit. If you exceed the limit, additional requests are rejected with a `429` error until in-flight requests complete. ## Default limits Every new account starts with a concurrency limit of **5 concurrent requests**. As you purchase credits, the platform automatically increases your limit based on the total amount of paid invoices from the last four weeks. Self-serve limits scale up to **40 concurrent requests**. ## Model-based limits Higher-cost models have a lower allowed concurrency. When you call a model that costs more than **\$5 per request**, your concurrency limit for that model is **one quarter** of your account limit. Requests to lower-cost models continue to use your full account limit, and the two limits are tracked independently. ## Increasing your limit For concurrency above 40, contact our support team. Get help raising your concurrency limit