# Fund a project or set a monthly limit

Give a Funded project budget, correct it, or cap a Tracked project per month. A Tracked project has no limit by default, and ATLAS records its cost. A monthly limit is optional.

## Before you begin

- You need the Owner, Admin or Account Manager role.
- Know whether the project is Funded or Tracked. The **Funding** tab exists only on Funded projects, and the **Billing** tab only on Tracked ones.

## Add or correct funds on a Funded project

1. Open the project and select the **Funding** tab.
2. Select **Add funds**.
3. Enter the **Amount**. It can't be zero. Use a negative amount to correct or reduce the funding.
4. Enter a **Reason**. It's required.
5. Submit.

**Result:** the entry is added to the **Allocation history** with its date, amount, reason, author and running total. Entries are never edited. You can download a top-up statement from the history row, and **Monthly cost reports** lists the monthly statements.

A total of zero means the project refuses traffic. You can allocate funds to an archived project, but traffic stays refused until you reactivate it. ATLAS refuses other changes to an archived project with `ERR-0126`. These include editing the project, its configuration or models, creating keys, adding members and changing member roles.

## Set or clear a monthly limit on a Tracked project

1. Open the project and select the **Billing** tab.
2. In **Monthly spending limit**, enter an amount greater than zero. The field reads **No limit** until you set one. To clear an existing limit, choose **No limit**.
3. Select **Save limit**.

**Result:** the limit applies to the calendar month in the organisation's [business time zone](https://docs.atlas.ilionx.dev/guides/admin/budget-and-cost-business-time-zone-and-statements.md). Once the month's spend reaches it, the gateway refuses requests with a `429` budget error (`402` for Anthropic-compatible clients) until the next month.

## Troubleshooting

The interface shows **Funding** only on Funded projects and **Billing** only on Tracked ones, so you meet these codes only through the API. Look up any code at `https://<atlas-host>/errors/<code>`, where `<atlas-host>` is your ATLAS host. [Errors](https://docs.atlas.ilionx.dev/reference/errors.md) explains how ATLAS reports them.

| Symptom                                       | Cause and remedy                                                           | Code       |
| --------------------------------------------- | -------------------------------------------------------------------------- | ---------- |
| An API call to allocate funds is refused      | The project is Tracked and has no funds. Set a monthly limit instead.      | `ERR-0087` |
| An API call to set a monthly limit is refused | The project is Funded and capped by its funding. Adjust its funds instead. | `ERR-0141` |

## Related

- [Create a project](https://docs.atlas.ilionx.dev/guides/admin/projects-create-a-project.md)
- [Manage project members](https://docs.atlas.ilionx.dev/guides/admin/projects-manage-members.md)
- [Two funding modes](https://docs.atlas.ilionx.dev/concepts/projects.md#two-funding-modes)
- [Projects](https://docs.atlas.ilionx.dev/concepts/projects.md)