The SimPRO + n8n + Xero Stack for Trades: Automating the Field Service Loop

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 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.

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

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:

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) when the invoice is created, you need n8n’s customization capabilities.

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.

Sources

• SimPRO API Webhooks Reference
• Xero Developer API Invoices Documentation