Build your own expense tracker with Claude.

They're the difference between a tracker and a mess.

1. Strip it. Whatever you paste into an AI goes to its company's servers. So download your statement as a file yourself, then delete your name, account and card numbers, UPI IDs, PAN and address before it goes anywhere. Never give any app or AI your bank login. A downloaded file beats a shared password, every single time.
2. Separate it. Not everything that leaves your account is spending. Money moved to your own savings isn't spent. Your SIP isn't spent, it's saved. And your credit card bill isn't new spending: you spent that money last month, on the card. Count it again and you've paid for the same dosa twice.
3. Check it. Claude is brilliant at reading "UPI-TEA STALL" and knowing it's food. It's less trustworthy at adding forty numbers in its head. So Claude sorts, formulas add, and the total gets checked against the statement. Claude is a calculator with a mouth, not an adviser.

One month, October 2026, 42 lines: a salary, rent, a car loan, a SIP, a card bill, a refund, and a lot of small UPI payments that each felt like nothing. Made up: no real bank, shop, employer or person. Run the whole method on this before you touch your own statement.

Opening balance ₹48,650.00. Closing balance ₹59,457.00. With your own statement: download it from your bank as CSV or Excel (PDF works too, but CSV is easier for Claude to read without mistakes), then strip it.

Open Claude, start a fresh chat, attach the statement and paste Prompt 1. Then the others, one after another, in the same chat. They work in any capable AI assistant. Nothing comes to us.

Prompt 1: sort every line

One category per line from a fixed list, so the AI can't invent "Vibes". Anything it isn't sure about goes to Unclear, and it has to ask you.

I'm attaching one month of my bank statement as a CSV file. I've removed my name,
account numbers and other personal details.

Don't recommend any bank, card, app, fund or product, and don't tell me what to buy.
Just sort and count.

Put every line into exactly one of these categories:
Income · Rent · EMI · Groceries · Eating out & delivery · Transport · Bills & utilities ·
Subscriptions · Shopping · Health · Family support · Cash · Savings & investments ·
Card bill payment · Transfer to own account · Refund · Unclear

Rules:
- A refund goes in Refund, and in a "Refund of" column say which category it refunds.
- Card bill payment, Transfer to own account and Savings & investments are NOT spending.
- If you aren't sure what a line is, put it in Unclear and ask me about it. Don't guess.

Give me a table with these columns: Date, Description, Debit, Credit, Category,
Refund of, Note (a short reason for any line you weren't sure about).
Don't skip any row. At the end, tell me how many rows you read from the file.

Prompt 2: check your own sums, then find the leaks

The balance has to tie before anything else can be trusted. Then the real spending, and the small payments nobody notices.

Now check your work.
1) Total debits and total credits. Then: opening balance + credits − debits. Does it
   equal the closing balance on the statement? Show the sum.
2) My real spending this month: everything except Income, Savings & investments,
   Card bill payment and Transfer to own account, with refunds taken off the category
   they refund. Give it by category, largest first, and the total.
3) Every repeat charge you can see (monthly or yearly). Say which is which.
4) Every category with more than 5 payments under ₹1,000.
For 3 and 4, show what each would cost over 12 months if the pattern continued.
Yearly charges count once a year, not twelve times. Don't judge my spending. Just count.

Prompt 3: build the tracker

Every total a formula, never a typed number, and one cell that checks the file against the statement. Claude needs file creation switched on in its settings; if it can't make the file, use our checker and sheet below instead.

Build me an Excel file (.xlsx) I can open in Excel or upload to Google Sheets,
with three tabs:
1) Transactions: every row with its category, as plain data.
2) Categories: the category list, a column saying "spending" or "not spending",
   and an empty Monthly budget column for me to fill in.
3) Summary: for each category, the total using SUMIFS formulas that read the
   Transactions tab. Never type a number into Summary. Add: total spending,
   total not-spending, and budget minus actual for each category.
Add one check cell that compares the sum of all debits in Transactions with the
statement's total debits, which I'll type into a cell next to it, and shows OK or CHECK.
No macros, no scripts, no links to anything outside the file.

Prompt 4: next month, same rules

This is what makes it a habit: ten minutes, chai still hot.

Here is next month's statement, stripped the same way. Use exactly the same
categories and rules as before. Give me only the new rows, as a table with the same
columns as my Transactions tab, so I can paste them underneath. Then list anything
new, anything Unclear, and any repeat charge that changed amount.

v1.0, 4 November 2026. Prompts tested on the mock statement; the models and what each got right or wrong are in our test notes.

Paste the table Claude made in Prompt 1, header row included. It can be a copy of Claude's table straight from the chat, CSV or tab-separated. We add it up here, check it against your statement, and show the spending the way the rules count it. It all runs on this page: nothing you paste is sent anywhere.

Siddharth, a product manager in Bengaluru (illustrative), and our mock October. One line is a mystery: "UPI-R KUMAR", ₹800. Was it a friend, a plumber, or the guy who sold him a cricket bat? Claude can't know, so Prompt 1 makes it ask. In our example it was the plumber: Bills & utilities.

So ₹46,449 of what left his account wasn't spending at all. That gap is why most of us think we're broke when we're not, or fine when we're not. And the tea and the delivery orders, each one loose change, add up to a bill nobody sent him. It's the chillar that walks out of your wallet in chappals, one coin at a time.

Illustrative, our calculation on the mock statement. "Over 12 months" assumes the month repeats; it's arithmetic, not a forecast.

Want the mock month already sorted, to compare with your AI's answer? Download our answer key (.csv).

No official figures: this tool is arithmetic on your own statement. The rules it uses are ours, written down so you can disagree with them.

• AI answers change from run to run. The same line can land in a different category next month. That's why the category list is fixed, the totals are formulas and the checks exist. Trust the check, not the vibe.
• Privacy is your job, every month. Strip the statement before it goes anywhere, and read your AI provider's data settings yourself. We never see what you paste into an AI, or into this page.
• A card statement and a bank statement together double count, unless the card bill stays "Card bill payment". Track the card's lines, or the bill. Never both.
• Long statements: an AI can skip rows. Compare the row count with your statement, every time.
• PDF statements are harder to read than CSV. If your bank offers CSV or Excel, use it.
• This is a tracker, not tax advice. If you freelance and want these categories for your tax return or business expenses, take them to a chartered accountant. In Europe, a local tax adviser.
• No bank, card, app or fund is recommended, here or in the prompts. Prompt 1 tells the AI not to.

Checker tested against the mock month worked by hand, the traps built into it (refund as income, card bill and own transfer as spending, an Unclear line, a missing row), and tables pasted as CSV, tab-separated and Markdown: 48 checks. v1.0, 4 November 2026.