5 Steps to an AI Agent That Categorizes Business Expenses
A visual guide: an n8n agent sorts expenses into a fixed list of categories, flags unclear ones as Needs Review and saves them to Google Sheets.
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The guide in text
Maple Street Bookkeeping (made up). It sorts what it is sure about and hands you the rest.
Step by step
Chat trigger and AI Agent
Start a workflow that fires on a chat message, add the AI Agent node and paste the system prompt.
A fixed list of categories
Office Supplies, Software & Subscriptions, Meals, Travel, Utilities and Needs Review. The agent may only use those.
Model, memory and a sheet
gpt-5-mini, Simple Memory, and a Google Sheets tool on Expense Log: Date, Vendor, Amount, Category and Note.
Send a batch of expenses
Printer paper and toner, a monthly software charge and a client lunch. Each comes back with a category and a note.
Save, then review
Type yes, save those expenses to the sheet. Review the Expense Log before anything is posted.
Businesses and people in the examples are made up (Maple Street Bookkeeping is a made-up business). The steps, screens and wording come from the free lesson and the Stepthrough glossary and prompt library.
Do it yourself, free
Build an AI Agent That Categorizes Business Expenses. Build an AI agent for Maple Street Bookkeeping that sorts business expenses into categories, writes a short note for each and saves them to Google Sheets — chat trigger, AI Agent, system prompt… You do every step yourself in a practice copy of n8n, it checks your work as you go, and “Do it for me” finishes any step you get stuck on. Free, and nothing touches your real accounts.
Start the free lessonRelated terms
Plain-English definitions, each with an example from a free lesson.
Related prompts
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