Expense categorization prompt: free ChatGPT template
Updated · By Robert Breen
Use this when you have a pile of card charges or bank lines to sort before the books can close. The AI is quick at the obvious ones (software subscriptions, a utility bill) and useful at writing a note for each. Where it goes wrong is guessing: filing a vague Amazon order as Office Supplies, or using a category your books don't have. This prompt limits it to your category list, gives unclear items a Needs Review bucket, and asks for a row count so nothing silently drops out.
The prompt
Copy it into ChatGPT (or Claude, Gemini or Copilot) and replace every [BLANK] with your own details. It uses the four parts from Prompt Writing 101: Role, Context, Task and Format.
Role: You are a careful bookkeeping assistant for [BUSINESS]. A person reviews every entry before it is posted. Context: Use only these categories, spelled exactly as written: [CATEGORIES]. Our rules for tricky items: [CATEGORY RULES]. If an expense could fit more than one category, or the description is too vague to tell, use Needs Review and say why. Don't change amounts, dates or vendor names, don't guess what something was for, and don't give tax advice, such as whether something is deductible. Task: Categorize every expense in the list below, in the same order, with one short note each. Format: A table with the columns Date, Vendor, Amount, Category, Note. The note is one sentence: what it appears to be for and anything I should check, like a missing receipt. After the table, write "Rows in: X. Rows out: Y." Here are the expenses, one per line: [EXPENSES]
Fill in the blanks
[BUSINESS]- Whose books these are, in a few words.
[CATEGORIES]- Your category or account names, copied from your accounting software so they match exactly. Include Needs Review.
[CATEGORY RULES]- The calls your bookkeeper already makes the same way every time, such as where client meals go or what to do with a bare "Amazon" charge.
[EXPENSES]- Date, vendor, amount and any description for each expense, one per line. Leave out card and account numbers.
Example, filled in
A made-up example from the free lesson Build an AI Agent That Categorizes Business Expenses. In the expense categorizer lesson, Maple Street Bookkeeping (a made-up firm) builds an n8n agent for this job. Here it does the same sort in a plain chat, with two harder items added.
Role: You are a careful bookkeeping assistant for Maple Street Bookkeeping, sorting the firm's own expenses. A person reviews every entry before it is posted. Context: Use only these categories, spelled exactly as written: Office Supplies, Software & Subscriptions, Meals, Travel, Utilities, Needs Review. Our rules for tricky items: client lunches go to Meals, with the client's name in the note if it's given. Amazon orders with no item description go to Needs Review. If an expense could fit more than one category, or the description is too vague to tell, use Needs Review and say why. Don't change amounts, dates or vendor names, don't guess what something was for, and don't give tax advice, such as whether something is deductible. Task: Categorize every expense in the list below, in the same order, with one short note each. Format: A table with the columns Date, Vendor, Amount, Category, Note. The note is one sentence: what it appears to be for and anything I should check, like a missing receipt. After the table, write "Rows in: X. Rows out: Y." Here are the expenses, one per line: Sep 22, Corner Office Supply, $64.18, printer paper and toner Sep 23, CloudLedger, $45.00, monthly accounting software Sep 24, Harbor Street Cafe, $38.50, lunch with a client Sep 25, Amazon, $129.99, no description Sep 26, PennPower, $212.40, office electric bill
What a good answer looks like
- Five rows, in the order you pasted them, with amounts identical to yours.
- The Amazon charge in Needs Review with a reason: no item description, so it can't be placed.
- Short, useful notes, such as "Client lunch; client name not given, add it before posting."
- "Rows in: 5. Rows out: 5." at the bottom.
How to check it before you use it
An AI draft can sound right and still say something you never told it. Use the habit from the Reply Faster lesson: check every promise, name, date and number against what you gave it before anything goes out.
- Compare the row count with your list. A long paste is where items most often go missing.
- Scan the Amount column against your source. The AI should copy amounts, never retype or round them.
- Look at every Needs Review row yourself; that's the point of the bucket. Then spot-check a few confident ones too.
- Treat categories as bookkeeping labels, not tax decisions. Questions about deductibility go to your accountant.
Why this prompt works
This is text classification with a fixed list, and the fixed list is what keeps it honest: the AI can't invent a category, and Needs Review gives it a safe answer when it doesn't know. The rules blank is where your chart of accounts habits live, so the same charge lands in the same place every month.
Practice it in the free lesson
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, model, memory, and the… You do every step yourself in a practice copy of n8n, and nothing touches your real accounts.
Also useful: AI Receipt Extractor: Receipts to Google Sheets with n8n
Terms used here
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