How to Build an AI Invoice Assistant with Make.com

This step-by-step guide shows you how to use make.com to create an AI-powered invoice assistant that drafts, edits, and emails invoices automatically with ChatGPT and your favorite tools.

You will learn how to turn unstructured text into structured invoice data, let AI generate invoice drafts, and send PDFs to your customers without manual copy-paste work.

What You Will Build with Make.com

Using make.com, you will create an automation that can:

• Accept invoice details in free-form text or from other apps
• Convert that text into structured invoice data using AI
• Generate a clean invoice draft with ChatGPT
• Store invoice data in your systems
• Send a ready-to-review or final invoice by email

The goal is to remove repetitive steps in your invoicing process, while still keeping you in control of the final output.

Prerequisites for the Make.com Invoice Assistant

Before you start building on make.com, prepare the following:

• A make.com account with access to scenarios and apps
• An OpenAI or compatible ChatGPT API key
• An email service connected to make.com (Gmail, Outlook, or SMTP)
• Optional: A document or accounting tool (such as Google Docs or a database) connected to make.com

Once these are ready, you can begin building your automation flow.

Step 1: Design the Workflow on Make.com

Start by sketching how you want invoices to move through your system. This helps you decide which modules and routes in make.com you will need.

A typical AI invoice workflow includes:

1. Trigger: When a user submits invoice details
2. AI processing: Clean and structure the data
3. Draft generation: Have ChatGPT format the invoice text
4. Storage: Save invoice data to a spreadsheet or database
5. Email: Send the invoice to the customer

Think about where the initial invoice request will come from, and how much human review is required before an invoice is sent.

Step 2: Create the Trigger in Make.com

The trigger starts your scenario on make.com. Common options include:

• Webhook trigger: Capture data from a form, chatbot, or another system
• Watch module: Monitor a spreadsheet, CRM, or ticketing tool for new invoice requests
• Manual trigger: Run the scenario on demand when you need to create an invoice

Configure the trigger so it collects all essential invoice details, even if they are provided in messy or unstructured text.

Step 3: Use AI to Structure Invoice Data on Make.com

Next, connect a ChatGPT or OpenAI module in make.com to transform raw text into clean invoice fields. The goal is to extract key elements such as:

• Customer name and contact details
• Invoice date and due date
• Line items, quantities, and prices
• Tax, discounts, and totals

Prompting ChatGPT Effectively in Make.com

Inside your AI module on make.com, use a clear system or user prompt. For example:

• Explain that the model must output valid JSON
• List the exact fields you want (customer_name, items, total, etc.)
• Define formats for dates, currency, and numbers

This structured output makes it easier to map values across other modules in your automation.

Step 4: Generate the Invoice Draft Text

Once you have structured data, add another AI step in make.com to generate a polished invoice draft. Here you can:

• Provide your brand voice and tone guidelines
• Insert dynamic fields such as customer name and totals
• Add payment terms and instructions

Ask ChatGPT to return a clear, formatted body text that is ready to send in an email or to insert into a document.

Optional: Create a Document Template with Make.com

If you prefer PDF invoices or branded documents, you can:

• Use a document generation app integrated with make.com
• Fill predefined placeholders with the structured invoice data
• Export the finished invoice as a PDF file

This approach keeps the invoice layout consistent across all your customers.

Step 5: Store Invoice Data from Make.com

Good invoicing automation also keeps records in a system of your choice. Within make.com, add modules to:

• Append a row to a spreadsheet for each new invoice
• Insert a record into a database table
• Update your CRM or accounting tool with invoice status

Map the structured fields from your AI step directly into the storage module. This gives you visibility and reporting on all generated invoices.

Step 6: Email the Invoice Automatically

Finally, connect your email module in make.com. Configure it to:

• Use the AI-generated invoice text as the email body
• Attach a PDF invoice if you created one
• Send to the customer email address extracted by AI
• CC or BCC internal stakeholders if needed

Include a clear subject line, such as “Invoice #[InvoiceNumber] from [Your Company]”. You can use variables mapped from previous modules.

Adding a Human Review Step in Make.com

If you want extra control, insert a manual approval or review step in make.com:

• Pause the scenario and send the draft to your internal team
• Let a human approve, edit, or reject the draft
• Continue the automation only after confirmation

This keeps you compliant with internal policies while still saving time.

Best Practices for AI Invoices on Make.com

To make your invoice assistant reliable and safe, follow these guidelines:

• Validate totals: Recalculate line items and totals with native modules, not only AI output.
• Handle errors: Add error routes in make.com to catch missing or inconsistent data.
• Log activity: Store scenario runs, timestamps, and statuses for audits.
• Protect data: Limit who can access your scenario and connected accounts.

Regularly test your flows with different invoice examples to verify that extraction and formatting remain accurate.

Troubleshooting Your Make.com Invoice Scenario

If your scenario does not behave as expected, check the following:

• Review input data from the trigger to ensure all details are present
• Inspect AI prompts for clarity and field definitions
• Use the execution inspector in make.com to see each module’s output
• Refine mapping between AI output and storage or email modules

Most issues come from incomplete prompts or inconsistent data formats, both of which you can fix by tightening your instructions and validation steps.

Where to Learn More

For the original tutorial and additional examples, see the official guide on building an invoice AI assistant with ChatGPT and automations: Make.com invoice AI assistant tutorial.

If you want expert help designing scalable automation architectures or AI-assisted workflows, you can also explore consulting services at Consultevo, which specializes in automation, AI, and integration strategies.

Next Steps with Make.com

By following these steps, you now have a clear blueprint to build an AI invoice assistant on make.com that reduces manual work while preserving accuracy and control.

From here, you can extend your scenario to handle recurring invoices, multiple currencies, or additional document types, all orchestrated through make.com and your preferred AI models.

Need Help With Make.com?

If you want expert help building, automating, or scaling your Make scenarios, work with ConsultEvo — certified workflow and automation specialists.

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