> ## Documentation Index
> Fetch the complete documentation index at: https://developers.pleo.io/llms.txt
> Use this file to discover all available pages before exploring further.

# AS/ERP Integration: Overview

export const NoteCallout = ({title, children}) => <div className="callout-box callout-note">
    <div className="callout-row">
      <span className="callout-icon">
        <svg width="22" height="22" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" fill="currentColor"><path d="M208,104a79.86,79.86,0,0,1-30.59,62.92A24.29,24.29,0,0,0,168,186v6a8,8,0,0,1-8,8H96a8,8,0,0,1-8-8v-6a24.11,24.11,0,0,0-9.3-19A79.87,79.87,0,0,1,48,104.45C47.76,61.09,82.72,25,126.07,24A80,80,0,0,1,208,104Z" opacity="0.2" /><path d="M176,232a8,8,0,0,1-8,8H88a8,8,0,0,1,0-16h80A8,8,0,0,1,176,232Zm40-128a87.55,87.55,0,0,1-33.64,69.21A16.24,16.24,0,0,0,176,186v6a16,16,0,0,1-16,16H96a16,16,0,0,1-16-16v-6a16,16,0,0,0-6.23-12.66A87.59,87.59,0,0,1,40,104.49C39.74,56.83,78.26,17.14,125.88,16A88,88,0,0,1,216,104Zm-16,0a72,72,0,0,0-73.74-72c-39,.92-70.47,33.39-70.26,72.39a71.65,71.65,0,0,0,27.64,56.3A32,32,0,0,1,96,186v6h64v-6a32.15,32.15,0,0,1,12.47-25.35A71.65,71.65,0,0,0,200,104Zm-16.11-9.34a57.6,57.6,0,0,0-46.56-46.55,8,8,0,0,0-2.66,15.78c16.57,2.79,30.63,16.85,33.44,33.45A8,8,0,0,0,176,104a9,9,0,0,0,1.35-.11A8,8,0,0,0,183.89,94.66Z" /></svg>
      </span>
      <div>
        {title && <div className="callout-title">
            {title}
          </div>}
        <div className="callout-body">
          {children}
        </div>
      </div>
    </div>
  </div>;

export const RememberCallout = ({title, children}) => <div className="callout-box callout-remember">
    <div className="callout-row">
      <span className="callout-icon">
        <svg width="22" height="22" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" fill="currentColor"><path d="M229.66,98.34,172.39,155.8c11.46,22.93-1.72,45.86-10.11,57a8,8,0,0,1-12,.83L42.34,105.76A8,8,0,0,1,43,93.85c29.65-23.92,57.4-10,57.4-10l57.27-57.46a8,8,0,0,1,11.31,0L229.66,87A8,8,0,0,1,229.66,98.34Z" opacity="0.2" /><path d="M235.32,81.37,174.63,20.69a16,16,0,0,0-22.63,0L98.37,74.49c-10.66-3.34-35-7.37-60.4,13.14a16,16,0,0,0-1.29,23.78L85,159.71,42.34,202.34a8,8,0,0,0,11.32,11.32L96.29,171l48.29,48.29A16,16,0,0,0,155.9,224c.38,0,.75,0,1.13,0a15.93,15.93,0,0,0,11.64-6.33c19.64-26.1,17.75-47.32,13.19-60L235.33,104A16,16,0,0,0,235.32,81.37ZM224,92.69h0l-57.27,57.46a8,8,0,0,0-1.49,9.22c9.46,18.93-1.8,38.59-9.34,48.62L48,100.08c12.08-9.74,23.64-12.31,32.48-12.31A40.13,40.13,0,0,1,96.81,91a8,8,0,0,0,9.25-1.51L163.32,32,224,92.68Z" /></svg>
      </span>
      <div>
        {title && <div className="callout-title">
            {title}
          </div>}
        <div className="callout-body">
          {children}
        </div>
      </div>
    </div>
  </div>;

This page provides a **high-level overview** of custom Accounting Integrations between Pleo and external Accounting Systems (AS) or Enterprise Resource Planning (ERP) systems.

It explains **what accounting integrations are**, **which integration levels are available**, and **where to go next** depending on your implementation needs.

## What Is an Accounting Integration?

An Accounting Integration allows an ERP or Accounting System to **receive accounting-ready data from Pleo** using Pleo APIs.

These integrations are typically used when:

* No pre-built integration exists
* Custom bookkeeping logic is required
* Advanced automation or synchronisation is needed
* The ERP system requires a bespoke deployment model

Accounting Integrations are **export-driven** and focus on moving expenses, attachments, and related accounting data from Pleo into an external system in a predictable and auditable way.

<NoteCallout title="Pre-built Integrations">
  If your system is supported out of the box, you may prefer a [pre-built integration](/docs/current/how-tos/how-to-connect-pleo-to-pre-built-as-systems).
</NoteCallout>

## Integration Levels

Accounting Integrations can be implemented at different **levels**, depending on which APIs are used and how much automation is required.

| Level   | Export | Tags | Categories | Vendors | Corresponding APIs                                                |
| :------ | :----- | :--- | :--------- | :------ | :---------------------------------------------------------------- |
| Level 1 | ✅      |      |            |         | Export API                                                        |
| Level 2 | ✅      | ✅    |            |         | Export API + Tags API                                             |
| Level 3 | ✅      | ✅    | ✅          |         | Export API + Tags API + Accounts API + Tax Code API               |
| Level 4 | ✅      | ✅    | ✅          | ✅       | Export API + Tags API + Accounts API + Tax Code API + Vendors API |

**How to choose a level:**

* **Level 1**\
  Enables exporting expenses and attachments. Suitable for basic accounting workflows.

* **Level 2 (recommended minimum)**\
  Adds Tags Sync, which syncs Accounting Dimensions from the Accounting System into Pleo as Tags. Users assign tags when they submit an expense; bookkeepers can assign or update them further before export.

* **Level 3**\
  Adds Chart of Accounts Sync and Tax Code Sync. Chart of Accounts are synced from the Accounting System into Pleo and mapped to expense categories; users assign a category when they submit an expense and bookkeepers can assign or update it before export. Accounts can optionally carry a `taxCodeExternalId` as a reference to a tax code in the Accounting System. Tax codes are synced separately via the Tax Code API.

* **Level 4**\
  Adds Vendor Sync, which is bi-directional. Vendors are synced from the Accounting System into Pleo. The integration can also listen for new vendors via the `v1.vendor.created` webhook and update the Accounting System with the details.

## Deployment Overview

Accounting Integrations can be deployed in different ways depending on the target ERP or Accounting System.

At a high level, integrations are deployed either:

* **As a module / on-premises**, hosted inside the ERP environment
* **On a cloud platform**, hosted externally and connected through OAuth 2.0

Each [deployment model](/docs/current/getting-started/accounting-integrations-deployment-decisions) affects how users authenticate, where configuration lives, and how authorisation is handled.

## Authentication & Authorisation

All Accounting Integrations use **OAuth 2.0** to securely access Pleo APIs.

* Users authorise access from within Pleo
* Tokens are issued and managed by the integration
* Scopes determine which APIs and data can be accessed

Authentication behaviour varies slightly depending on deployment model, but **OAuth 2.0 remains the single authorisation mechanism**.

***

## What Comes Next?

Start by getting access to the staging environment and setting up authentication, then build up through the integration levels in order.

**1. Get access**

* [OAuth 2.0 Access to Staging](/docs/current/guides/environment-access/staging-oauth-workflow)
* [OAuth 2.0 Setup Workflow Guide](/docs/current/guides/oauth-workflow-guide)

**2. Level 1: Export Integration**

* [Integration Design: Export Overview](/docs/current/integration-design/exports/integration-design-exports-overview)
* [Export Integration Workflow Guide](/docs/current/guides/export-integration-workflow-guide)

**3. Level 2: Tags Sync**

* [Integration Design: Tags Sync Overview](/docs/current/integration-design/accounting-integrations/imports/tags/integration-design-tags-overview)
* [Tags Sync Workflow Guide](/docs/current/guides/accounting-integrations/imports/tags-sync-workflow-guide)

**4. Level 3: Chart of Accounts and Tax Code Sync**

**4.1 Chart of Accounts Sync**

* [Integration Design: Chart of Accounts Sync Overview](/docs/current/integration-design/accounting-integrations/imports/accounts/integration-design-accounts-overview)
* [Chart of Accounts Sync Workflow Guide](/docs/current/guides/accounting-integrations/imports/accounts-sync-workflow-guide)

**4.2 Tax Code Sync**

* [Integration Design: Tax Sync Overview](/docs/current/integration-design/accounting-integrations/imports/tax-codes/integration-design-tax-sync-overview)
* [Tax Sync Workflow Guide](/docs/current/guides/accounting-integrations/imports/tax-sync-workflow-guide)

**5. Level 4: Vendor Sync**

* [Vendors API Reference](/reference/vendor/vendors-api-overview)

***

## Related Reading

* [Accounting Integration Deployment Decisions](/docs/current/getting-started/accounting-integrations-deployment-decisions)
* [AS/ERP Processing Workflow Guide](/docs/current/guides/accounting-system-processing-workflow-guide)

***