Gemini API 429 monthly spending cap exceeded despite Tier 1 and prepaid balance

Gemini API
1

Hello,

I am experiencing a billing issue with the Gemini API.

My project is on Paid Tier 1 and uses prepaid billing.

Current status:

  • Paid Tier 1 is active

  • €10 prepaid balance is available

  • Monthly project spend cap is set to €10

  • AI Studio shows €0.00 / €10.00 project spend

  • The API key belongs to this exact paid project

  • The billing account and Gemini API project are linked correctly

  • I am using Gemini 3.1 Flash TTS

However, every API request still returns:

429 RESOURCE_EXHAUSTED

“Your project has exceeded its monthly spending cap.”

I have already waited for the billing changes to propagate, but the error remains.

Could you please check whether the billing/spend-cap status for this project is out of sync and advise how to resolve it?

I can provide the project ID privately if required.

Thank you.

2

Please check your DMs

3

Hi @rolf1,

Do you have multiple projects under this billing account? If so, what is the monthly spending cap set on each one?