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# Test an import before integrating it with the sandbox

| **Summary.** The sandbox lets you import one or more billing Excel files into a test environment, measure their impact on your figures, and integrate them only if the result is right. Until you confirm, your production figures don't change.

## What the sandbox is for

Importing a file directly into Fincome changes your KPIs immediately, including those already shared with your teams or in your reports. The sandbox adds a control step in between:

* you load your files into a space isolated from your production;
* Fincome computes the combined effect of these files on your figures;
* you then decide to integrate the files or discard everything.

Common use cases: loading historical data, an invoice correction file, adding a new entity, or a complementary import while your account is already connected to a billing tool (Pennylane, Stripe…).

## Open the sandbox

1. Click the **Settings** icon (gear) at the bottom left.
2. Stay on the **Data Sources** tab.
3. Click **Open sandbox**, at the top right of the invoicing systems table.

The **Import sandbox** page opens (feature in *Preview*).

## Test your files

1. Click **Add Excel file** and select your billing file, in the usual import template format (see [Prepare my file](https://help.fincome.co/en/article/prepare-my-file-65s5k8/)).
2. The file appears in the **Staged files** list. You can add more: Fincome always computes the effect of **all** staged files together.
3. Review the impact shown below the list to compare the result with your current figures.
4. Remove or add files to see how the figures move.

## Integrate or discard

* **Integrate N files**: the staged files are integrated into your production. Your figures are then recalculated, as with a standard import.
* **Discard sandbox**: the sandbox is emptied, nothing is integrated and your production stays unchanged.

| Good to know: as long as you haven't clicked **Integrate**, no production data is modified. You can test as many file combinations as you need.

## Limits

* **Excel files only.** The sandbox tests billing imports in Excel format. It doesn't apply to data synced by a connector or sent through the API.
* **Calculation options can't be tested.** The sandbox computes the impact of your files with your current calculation options. To measure the effect of changing an option (churn recognition, discounts, etc.), change it in **Settings > Calculation parameters** (see [Manage calculation options](https://help.fincome.co/en/article/manage-calculation-options-1ffoqbf/)).
* **Large volumes.** For a very large file (several hundred thousand rows), split it into 3 or 4 files and add them one after the other in the sandbox.

## FAQ and common errors

**A red banner names my file, what should I do?**
The file was rejected at validation (missing column, inconsistent value, duplicate ID…). Download the error report offered: it lists the rows and columns to fix. Fix the file, remove the old version from the list and add the new one.

**The message "The sandbox could not be computed" appears, with no error report.**
In this case the problem doesn't come from your file's content but from the sandbox computation. Write to us from the chat at the bottom right, with the file name and the time of the attempt, so the technical team can find the cause.

**My figures didn't change after the import into the sandbox, is that normal?**
Yes. Files stay in the sandbox until you click **Integrate**. Your dashboards, reports and exports keep showing your production figures.

**Who can use the sandbox?**
Users with access to **Settings**, meaning the account administrators (see [Manage roles](https://help.fincome.co/en/article/manage-roles-z4sxxm/)).

## Related articles

* [Prepare my file](https://help.fincome.co/en/article/prepare-my-file-65s5k8/)
* [Import my file](https://help.fincome.co/en/article/import-my-file-p8jf4p/)
* [Manage calculation options](https://help.fincome.co/en/article/manage-calculation-options-1ffoqbf/)
* [Manual edits in Fincome](https://help.fincome.co/en/article/manual-edits-in-fincome-how-it-works-17uq4t7/)