429 RESOURCE_EXHAUSTED "prepayment credits are depleted" despite active billing and $0 spent

Gemini API
1

Project ID: gen-lang-client-05779752..
Billing account ID: 01C1CE-8680D4-5AE8..

I upgraded from free trial to a full paid account today (confirmed via email
“Gracias por actualizar a una cuenta pagada”). The one-time prepayment of
COP 100,000 was confirmed received (payment confirmation email received).
Monthly spend limit is set to COP 60,000 with COP 0.00 used.

Every call to generateContent using gemini-2.5-flash-image (Nano Banana)
returns:

429 RESOURCE_EXHAUSTED: “Your prepayment credits are depleted.”

This happens even on text-only models like gemini-flash-lite-latest, which
worked fine before I enabled billing today.

models.list() works fine and returns all models correctly.

This matches the billing sync issue reported by other developers recently.
Could you please perform a manual billing sync on this project?

2

Hello @Mauricio_Lopez ,

Note: There is no manual billing sync at our end.

This error usually comes if you made the payment to GCP billing instead of AI Studio billing. Kindly check.

3

Thanks for the clarification. I see on the “Gemini API Billing” page that the
available credit is COP 0, separate from my GCP billing account (where I did
make the one-time prepayment of COP 100,000 and was upgraded to paid Tier 1).

The warning message says “A credit balance greater than USD 0 is required to
resume service. If eligible Google Cloud credits exist, they will be applied
first” — should my GCP prepayment show up here as eligible credit, or are
these completely separate credit systems that require separate purchases?
I want to confirm before buying additional credits whether the payment I
already made should be covering this.

4

Hello @Mauricio_Lopez ,

Google Cloud Billing payments and the AIS prepaid wallet are separate systems that require separate purchases. i.e. Payments made directly to your Google Cloud billing account operate do not fund your AIS prepaid wallet. The payment made to Google Cloud Billing will not cover API usage while your AIS prepaid wallet balance is zero. Eligible Google Cloud promotional or trial credits require an active AIS prepaid wallet balance (> $0) to be unlocked. Once you deposit the required minimum prepayment directly into your AIS prepaid wallet at https://aistudio.google.com/billing, eligible Google Cloud credits will be applied first before deducting from your deposited prepaid funds.