OpenAI lets Plus and Pro subscribers buy extra Codex usage credits, with optional auto top-up

If you use Codex regularly, you have probably hit the wall before. You are mid-task, something complex is running, and then your plan’s included usage runs out. Up until now, the options were limited: wait for the limit to reset, or upgrade your plan entirely.

OpenAI has added a third option. ChatGPT Plus and Pro subscribers can now purchase additional usage credits for Codex directly, without changing their plan. There is also an optional auto top-up that replenishes your credit balance automatically when it drops below a threshold you choose.

What are these credits, exactly?

Credits are a pay-as-you-go layer that sits on top of your existing plan allowance. Your plan’s included usage works exactly as before. Credits only come into play once that included allowance is exhausted.

Right now, credits purchased this way can be used with two things: Codex (for Plus and Pro subscribers) and ChatGPT for Excel. The balance is shared between them, so credits bought while working in Codex can equally be spent on ChatGPT for Excel tasks, and vice versa. Credits are valid for 12 months from purchase.

Pricing follows token consumption rather than a per-message model. OpenAI updated Codex pricing in April 2026 to align with API token usage, calculated across input tokens, cached input tokens, and output tokens. How quickly you burn through credits depends heavily on what you are doing. Simple scripts or short functions use a fraction of what a long-running task across a large codebase would consume. As a rough benchmark, OpenAI estimates Codex costs around $100 to $200 per developer per month on average, but actual usage varies widely.

How auto top-up works

The auto top-up feature is the more interesting part for anyone using Codex as a regular part of their workflow.

You set a minimum balance threshold. When your credit balance falls below that number, the system automatically purchases just enough credits to bring the balance back up to your chosen target. It uses whatever payment method you have set as your default. You do not need to do anything manually.

One thing worth knowing: if your balance is already below the minimum when you first turn auto top-up on, a purchase will happen immediately rather than waiting for the next time you hit the threshold. So it is worth checking your current balance before enabling it if you want to avoid an unexpected charge.

You can manage the whole thing from the Codex Settings usage dashboard on ChatGPT web, where you can also see your remaining credit balance and recent usage.

Who this is and is not for

This feature is exclusive to ChatGPT Plus and Pro subscribers. Free and Go users who hit their Codex limits are prompted to upgrade their plan rather than purchase credits. Some Plus and Pro users may also see a prompt to upgrade depending on their account status, so not every Plus subscriber will necessarily have the credit purchase option available immediately.

For users who are well within their monthly Codex usage, none of this changes anything. Your plan works as it always has.

For heavier Codex users, particularly developers running multi-step agentic tasks, working across larger codebases, or using fast mode, the credit system offers a straightforward way to keep working without interruption. The auto top-up option makes that even more seamless, removing the need to manually monitor your balance and top up before running something substantial.

It is also worth noting that image generation within Codex draws from the same credit balance once your included limits are used up, so it is not only text-based coding tasks that consume credits.

A few practical notes

• Usage from Codex, ChatGPT for Excel, and Workspace Agents all count toward the same agentic usage limit in your plan
• Local messages and cloud tasks share a five-hour usage window, with additional weekly limits that may apply
• A typical ChatGPT for Excel task using GPT-5.5 consumes roughly 5 to 30 credits per task
• Students at US and Canadian universities can claim $100 in ChatGPT credits (2,500 credits) for Codex through the Codex for Students programme, verified via SheerID

The bigger picture

Codex itself launched in May 2025 as a cloud-based autonomous coding agent built on GPT-5 family models. It runs multi-step software tasks in isolated sandboxes and is a different product entirely from the original 2021 Codex model. Adding a credits layer is a logical step as OpenAI moves Codex from a feature you occasionally use to something closer to infrastructure for developers who depend on it daily.

The credit and auto top-up system gives power users more control over their usage without forcing them into a more expensive plan tier. For casual users, it is easy to ignore. For anyone building seriously with Codex, it removes one of the more frustrating friction points.