Bill Approval Automation · AI + Workflow Automation

Taking the manual work out of accounts payable.

An AI-assisted accounts payable system that takes an invoice from the inbox through extraction, accounting classification, approval and creation in Xero — while keeping a human in control where it matters.

  • Workflow Automation
  • AI Integration
  • Finance Operations
  • Rapid Prototyping
n8n — Bill approval workflow

  1. 01

    Gmail trigger

    New email

  2. 02

    Attachment filter

    PDF invoice

  3. 03

    AI extraction

    Invoice → data

  4. 04

    Xero lookup

    Supplier + duplicates

  5. 05

    Chart of Accounts

    AI classification

  6. 06 · human

    Approval

    Human decision

  7. 07

    Create bill

    Xero API

Gmail → AI extraction → Xero lookup → classification → approval → bill

The automation is orchestrated in n8n — the diagram above maps the stages of the working workflow.

The starting point

It started with one question.

“How is AI affecting your world?”

That question, asked during a conversation with an accountant, quickly turned into a discussion about one of the most repetitive workflows his clients deal with: processing supplier invoices.

A person may need to monitor an inbox, find invoice attachments, identify the supplier, inspect the accounting system, determine the correct Chart of Accounts, request approval, wait for a response and finally enter the approved invoice into Xero as a draft bill.

The individual steps aren't particularly difficult. The problem is the amount of manual coordination required to repeat them reliably, several times a day.

The problem

A simple process with too many manual steps.

  1. 1Invoice arrives
  2. 2Open attachment
  3. 3Read invoice
  4. 4Identify supplier
  5. 5Determine Chart of Accounts
  6. 6Request approval
  7. 7Wait / follow up
  8. 8Enter bill in Xero

Accounting platforms already automate parts of this process, but real businesses often have their own approval rules, accounting conventions and exceptions.

That means the remaining gaps are frequently filled with email, manual checks and human memory.

The opportunity wasn't to replace the accounting platform. It was to automate the workflow around it.

From problem to working flow

A working prototype in under an hour.

Instead of starting with a lengthy requirements document, the manual process was mapped directly into an executable workflow using n8n, test Gmail accounts, Xero and AI document extraction.

Within the initial session, the prototype could detect an incoming invoice, extract its information, map the accounting treatment, request approval and create an approved bill in Xero.

The surprising part wasn't that the automation was technically possible. It was how quickly a real business process could be turned into working software.

To be clear: “under an hour” refers to the initial end-to-end working prototype — not a polished, production-hardened implementation.

The system

From inbox to accounting software.

n8n — Bill approval workflow

  1. 01

    Gmail trigger

    New email

  2. 02

    Attachment filter

    PDF invoice

  3. 03

    AI extraction

    Invoice → data

  4. 04

    Xero lookup

    Supplier + duplicates

  5. 05

    Chart of Accounts

    AI classification

  6. 06 · human

    Approval

    Human decision

  7. 07

    Create bill

    Xero API

Gmail → AI extraction → Xero lookup → classification → approval → bill

01

Detect the invoice

The workflow monitors incoming email and identifies messages containing PDF invoices.

Gmail trigger · attachment detection

02

Extract the invoice data

AI reads the invoice PDF and converts information such as supplier, invoice number, dates, amounts and other relevant fields into structured data the workflow can use. The current prototype uses an LLM-based document extraction step.

LLM document extraction

03

Check the supplier and duplicates

The workflow checks Xero for supplier information and verifies whether the invoice appears to have already been processed. Potential duplicates are flagged before they continue, rather than blindly creating another bill from the same invoice.

Xero lookup · duplicate check

04

Determine the Chart of Accounts

The workflow retrieves the client's Xero Chart of Accounts and provides the relevant accounting context to AI to determine an appropriate account classification. The response is parsed and evaluated before the invoice moves forward — an assisted decision, with confidence thresholds able to route uncertain cases to human review.

Accounting context · assisted classification

05

Ask for human approval

Rather than allowing AI to post financial records autonomously, the workflow sends the invoice through an approval step. The relevant person can approve or reject it before anything is created in Xero. AI assists. Humans remain in control.

Approval routing

06

Create the bill

Once approved, the workflow builds the required bill data, creates the bill in Xero and sends confirmation. Rejected invoices follow a separate communication path rather than being posted.

Xero API · confirmation

Design principle

Automate the routine. Escalate the uncertain.

Financial automation shouldn't mean blindly trusting an AI response. The workflow is designed around a combination of automation, confidence and human control.

Automate deterministic work

Email monitoring, PDF handling, system lookups, duplicate checks and API calls can run automatically.

Use AI where interpretation is needed

AI helps turn unstructured invoice documents and accounting context into structured decisions.

Keep humans at important decision points

Approval steps and confidence thresholds provide a path for human review instead of forcing uncertain decisions through automatically.

Why this matters

The workflow can adapt to the business.

The interesting problem wasn't whether Xero could create a bill. It was everything that happens before the bill reaches Xero.

Different businesses can have different approval thresholds, accounting conventions, suppliers, routing rules and exceptions. Traditionally those gaps either remain manual or require another piece of software.

Workflow automation makes it possible to build those business-specific rules around the systems a company already uses.

Accounting platform

  • System of record
  • Suppliers
  • Chart of Accounts
  • Bills
  • Financial data
+

Automation layer

  • Email intake
  • AI extraction
  • Classification
  • Custom rules
  • Approval routing
  • Exception handling
=

Result

Business-specific workflow

Current implementation

An automation system today. A product opportunity tomorrow.

The current implementation is orchestrated in n8n rather than through a dedicated standalone application. n8n acts as the workflow engine connecting Gmail, AI services and Xero while implementing the business rules and approval flow.

That was intentional for the prototype: the objective was to validate the workflow and demonstrate the value quickly before investing in a larger product build.

A future dedicated product could place a purpose-built interface around the automation layer for configuration, review, exception handling, audit history and multi-client management.

Built today

  • Email invoice ingestion
  • PDF/invoice information extraction
  • Supplier/Xero lookup
  • Duplicate detection
  • Chart of Accounts matching workflow
  • Approval routing
  • Xero bill creation
  • Approval/rejection communication

Potential product layer — not built

  • Client configuration interface
  • Approval dashboard
  • Exception queue
  • Audit history
  • Workflow configuration
  • Accountant multi-client management
  • Reporting and monitoring

Technology

Connecting the tools already in the workflow.

Orchestration
n8n
Email
Gmail
AI
LLM-based invoice extraction and accounting classification
Accounting
Xero API
Integration
REST APIs

The bigger idea

Custom software is becoming dramatically cheaper to test.

This project started as a conversation about a manual accounting process and became a working end-to-end prototype during the same session.

The individual technologies weren't new. Email automation, APIs, document processing and workflow engines have existed for years. What changed was the speed at which they could be combined with AI to solve a specific business problem.

That creates an interesting opportunity for small and medium businesses: instead of changing their processes to fit every piece of software they buy, increasingly they can build lightweight automation around the systems they already use.

Still moving information between systems by hand?

We help businesses turn repetitive workflows into practical software and automation.

Start a conversation
Back to all work