As an account administrator, you can define rules which trigger notifications when your account's usage exceeds a certain threshold. These rules are called "budgets".
Budgets are configured on a per-account basis. When a budget is triggered, any configured users will receive an email notification. Budget notifications are sent immediately after being triggered.
To see a list of all configured budgets in your account, first go to the Billing settings page by clicking on your avatar in the top right corner, then clicking on Billing.
On the Billing settings page, click the Budgets tab to see all configured budgets in your account:
To create a new budget, click the Add Budget button. Enter a name for the budget, then select a time period (either 'Daily' or 'Monthly') and a corresponding target amount, which is the amount of usage that will trigger a notification.
You can also configure threshold rules, which allow you to trigger notifications when usage exceeds a certain percentage of the target amount. For example, if you set a target amount of $1,000 and a threshold of 80%, you will also receive a notification when your usage exceeds $800.
A good rule-of-thumb for accounts that pay annually is to set a monthly budget of 1/12 (~8.3%) for your first budget.
If you have multiple thresholds defined, some thresholds may not be triggered if a higher threshold is triggered first. For example, if you have a target amount of $1,000 and thresholds of 80% and 90%, and your usage hits 95%, you will only receive a notification when your usage exceeds $900.
When creating a new budget, by default, all users will receive email notifications.
You can also specify particular users who should receive alerts by toggling the Specific users option and selecting them. Optionally, you can also add additional email addresses that should receive email notifications by entering the email address in the Custom email field.