This article goes over Facebook's Ad account spending limit.
About the Spending Limit
Setting an account spending limit is not available for users that make manual payments. If you have a prepaid balance, there will be no option available for you. The spending limit is a lifetime limit on the amount Facebook Ads can spend on all advertising campaigns The spending limit allows you to control your costs so that you do not overspend This means that the limit does not end per month; the budget you set lasts until it runs out or you stop it. There is a tracker in your payment settings that allow you to see how much you have spent
If your amount spent reaches its limit, the advertisements will pause and stop spending money. The advertisements will still be listed as active to allow for change, a reset, or the ability to resume immediately
How do I update the spending limit?
There are a few things you need to remember before you can set a limit on your ads account.
Your Facebook Ads account needs to be an admin to have the ability to update the account spending limit. If your ad account is set up with manual payments, you won't have the option to set a spending limit. You cannot set a spending limit that is less than 10% above what you have already spent. For example, if your current limit is $150 and you have spent $100, the minimum you can lower the limit to is $110.
Follow these steps to update your account spending limit:
Go to your Payment Settings in Ads Manager In the Set Your Account Spending Limit section, click change. Enter the limit you would like to use. Click Update Limit.
It takes 15 minutes to update and apply to your ads account. The amount that was already spent will be added to the new limit. In order to keep advertising, you will need to update your limit or reset your spend to $0.*Note: The maximum number of changes that you can make is ten per hour. If you try to change it more than 10 times, it will ask you to wait another hour before updating it again.