How do I set a monthly AI spending limit?

Create a hard budget that blocks or degrades AI calls before charges hit your provider bill — in under 5 minutes.

Goal: A monthly spending limit enforced at the proxy — so overspend is impossible, not just alerted.

Time: 5 minutes.

Step 1 — Go to Budgets and create a new budget

Open Dashboard → Budgets → New Budget.

Fill in the form:

Field	What to enter
Name	Something descriptive — `Engineering monthly`, `chatbot feature`, `Org total`
Monthly limit	Your budget in USD
Scope	See below
Enforcement	See below
Alert thresholds	`50, 80, 100` (you'll get email alerts at each)

Choosing the scope:

Scope	Use when
Global	One limit for your entire organisation's AI spend
Department	Limit a team — needs `X-Cost-Department: engineering` in your calls
Feature	Limit a single product feature — needs `X-Cost-Feature: chatbot` in your calls

Choosing enforcement:

Mode	What happens when the limit is hit
Alert	Call goes through, you get a notification. Good for monitoring.
Degrade	Call is rerouted to a cheaper model. Good for production features.
Block	Call returns 429. Good for experimental features and agents.

Start with Alert, graduate to Block

If you're not sure which to pick, start with Alert for 2 weeks to understand normal spend patterns. Then switch to Block or Degrade once you're confident in the limit.

Step 2 — Save and verify

Click Save. The budget appears on the Budgets page immediately.

To verify it's active, make a test API call through the proxy and check the response headers:

response = client.chat.completions.create(
    model="gpt-4o-mini",
    messages=[{"role": "user", "content": "hello"}],
    extra_headers={"X-Cost-Feature": "chatbot"}
)
# Header shows remaining budget across all matching limits
print(response.headers.get("x-cog-budget-remaining"))

You'll see the remaining budget in USD for this call's scope.

Step 3 — Test the enforcement (optional)

To verify the block mode works: temporarily set the budget to $0.01, make a call, confirm you get a 429. Then restore the real limit.

Useful follow-ups

Multiple levels — Add a department budget on top of feature budgets. The tightest limit always wins. See Hierarchical Budgets.
Agent workflows — Add a per-run limit so one runaway agent can't consume your entire feature budget. See Track Cost Per Agent Run.
Get alerted in Slack — Budget alerts can route to Slack instead of (or in addition to) email. See Slack Alerts.

Step 1 — Go to Budgets and create a new budget

Step 2 — Save and verify

Step 3 — Test the enforcement (optional)

Useful follow-ups

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