Advertising
Budget pacing
How a platform spreads a budget across the period, rather than spending it as fast as the auction allows.
What makes it wrong.
The mechanism, not the warning.
Daily budgets are averages on several platforms, not caps: a single day can exceed the stated amount as long as the period averages out. A day-level alert built on the daily budget as a ceiling fires on normal behaviour.
In detail.
Pacing smooths delivery so a daily budget is not exhausted in the first hours. It also means a budget raised mid-day does not take effect at the new rate immediately, and that a campaign can underspend while appearing budget-limited.
On a monthly view, the interaction between pacing and daily caps explains most of the gap between the budget set and the amount actually charged.