What happens when you disable billing on a Firebase project

Everything that costs money stops. Google's billing docs say that when you disable billing, "all of your Google Cloud and Google Maps Platform services are stopped and billing on that project stops." Your app stops working, and the bill stops growing. That's the point of a kill switch, and also its price.

• Paid Google Cloud services: Firebase says the project "loses access to any paid Google Cloud services, like Pub/Sub, Cloud Run, or BigQuery streaming for Analytics" (pricing plans).
• Free tier too, at the Cloud level: Google's tutorial on disabling billing warns it terminates "all Google Cloud services in the project, including Free Tier services."
• Deploys: on a downgraded Firebase project "you cannot do new deploys of any new or any existing Cloud Functions."
• Extra databases and buckets: the project loses access to non-default Realtime Database instances and non-default Cloud Storage buckets.

Not immediately, but Google won't promise it's safe either:

• For non-default Realtime Database instances and Storage buckets, Firebase says "the data in these instances and buckets doesn't get deleted".
• Google Cloud's general warning is broader: "some of your Google Cloud resources might be removed and become non-recoverable." Its kill switch tutorial puts it as "Resources might be irretrievably deleted."

The two statements cover different things, and neither describes every product. Treat a billing disconnection as an emergency brake, not a pause button: keep backups of what you can't lose (Firestore exports, Storage copies) before you rely on one.

For what you already used, yes. Costs that were incurred but not yet reported still arrive: Google notes you "might incur additional costs for usage that hasn't arrived at the time that all services are stopped."

1. Fix the cause first (the loop, the leaked key, the open rule).
2. Link the billing account again from Billing → Account management or the project's billing page. You need Project Billing Manager (or Owner) on the project and Billing Account User on the billing account.
3. Check each service: Google says re-enabling billing lets you "restart the resources", and some may need a manual restart or a redeploy.

Careful with permissions: if the account that disconnected billing is the only one that can reconnect it, keep that access. Google warns you "might not have the required permissions needed to later re-enable billing."

Because a disconnection is this drastic, it works best as the last of several steps. A Soft Kill lets your own app turn off its expensive parts first, so the hard stop only happens if that isn't enough.