**TL;DR —** For trades and field service businesses, manual bookkeeping is a major administrative bottleneck. When technicians complete jobs in **SimPRO**, office staff must copy details to **Xero** to generate invoices. By deploying **n8n** (see our [Zapier vs n8n vs Make comparison](/blog/zapier-vs-n8n-vs-make)) as the middleware connecting SimPRO webhooks to Xero APIs, you can automate this invoicing loop, eliminate manual errors, and accelerate cash flow.

---

## The Automation Loop: SimPRO to Xero

The automated integration relies on event-driven synchronization. Instead of running daily manual exports, the pipeline triggers every time a field technician changes a job's status.

```mermaid
graph TD
    A[SimPRO: Job Status Update] -->|Webhook Trigger| B(n8n Workflow Engine)
    B --> C[Xero API: Get/Create Contact]
    B --> D[Xero API: Generate Invoice]
    D --> E[Auto-Email Customer]
    
    style A fill:#00a3ad,stroke:#333,stroke-width:2px,color:#fff
    style B fill:#ea4b71,stroke:#333,stroke-width:2px,color:#fff
    style C fill:#13b5ea,stroke:#333,stroke-width:2px,color:#fff
    style D fill:#13b5ea,stroke:#333,stroke-width:2px,color:#fff
```

### The Invoicing Data Flow

| SimPRO Resource | n8n Mapping Logic | Xero Destination |
|---|---|---|
| Customer Name & Email | Match via email, create if missing | Customer Card |
| Job Description & ID | Append ID as invoice reference | Invoice Line Items |
| Labor & Material Costs | Extract sub-totals and tax rates | Line Item Quantities & Unit Price |
| Job Status: `Completed` | Trigger condition | Invoice Status: `Draft` (or `Submitted`) |

---

## Step-by-Step Integration Guide

Here is the exact n8n configuration flow to connect SimPRO and Xero:

### 1. Set Up the SimPRO Webhook Trigger
SimPRO does not have a native n8n trigger node, so we use the generic **Webhook** node in n8n.
1. Create a Webhook node in n8n. Copy the production URL.
2. Log into your SimPRO API settings and register a webhook subscription for the `job.status` update event, pointing it at your n8n webhook URL.

### 2. Match or Create the Xero Contact
To generate an invoice in Xero, the invoice must be associated with a valid Contact ID.
1. Use the n8n **Xero** node to query contacts by email: `EmailAddress == "{{ $json.body.customer.email }}"`.
2. Use an n8n **If** node to check if a contact ID was returned.
3. If no contact is found, route to a Xero **Create Contact** node using customer data from the SimPRO payload. If found, pass the existing Contact ID to the next node.

### 3. Parse Items & Create Invoice
SimPRO outputs line items (materials and labor) in an array. Xero expects line items in a specific JSON array structure.
1. Use n8n's **Code** node to format the line items array:

```javascript
const simproItems = $input.item.json.body.lineItems;
const xeroItems = simproItems.map(item => ({
  Description: item.name,
  Quantity: item.quantity,
  UnitAmount: item.price,
  AccountCode: "200", // Your standard Sales account code in Xero
  TaxType: item.taxRate > 0 ? "OUTPUT" : "NONE"
}));
return { json: { xeroItems } };
```

2. Add a Xero node set to **Create Invoice**. Map the formatted `xeroItems` array and set the Status to `AUTHORISED` (or `DRAFT` for review).

---

## FAQ

### Why use n8n instead of standard pre-built sync apps?
Standard pre-built connectors (like the native SimPRO-to-Xero integration) are rigid. If you want to customize tax mappings, add internal reference codes based on custom fields, or trigger an automated WhatsApp alert (via [Atharva AI](https://atharva.app) and the [WhatsApp Business API](/blog/whatsapp-business-api-indian-smbs)) when the invoice is created, you need n8n's customization capabilities. The same job-completed webhook can also fire a [WhatsApp Google review request](/blog/whatsapp-vs-email-review-requests) and feed your [reputation engine](https://vijayatechlabs.com/reputation-management?utm_source=blog&utm_medium=cta&utm_campaign=blog-reputation&utm_content=simpro-n8n-xero-trades-stack). For custom integrations, check our [field ops automation](https://vijayatechlabs.com/automation/field-ops) and [SimPRO + GoHighLevel sync guide](https://vijayatechlabs.com/integrations/simpro-gohighlevel-sync).

### Should I create the invoice as Draft or Authorised?
We recommend starting with `DRAFT`. This creates the invoice in Xero but allows your accounts team to quickly review the invoice lines for accuracy before sending it to the client. Once trust is established, you can change the status parameter to `AUTHORISED` to automatically email it.

---

## Related reading

- [GMB automation for service businesses](/blog/google-my-business-automation-service-businesses)
- [Why Google Map Pack beats local PPC](/blog/why-google-map-pack-beats-local-ppc)
- [WhatsApp vs email review requests](/blog/whatsapp-vs-email-review-requests)
- [Reputation Management product](https://vijayatechlabs.com/reputation-management?utm_source=blog&utm_medium=cta&utm_campaign=blog-reputation&utm_content=simpro-n8n-xero-trades-stack)

---

## Sources
- [SimPRO API Webhooks Reference](https://developer.simprogroup.com/apidoc/)
- [Xero Developer API Invoices Documentation](https://developer.xero.com/documentation/api/accounting/invoices)