Your month, in plain categories
By the end of this lesson you will have one month of your own spending sorted into plain categories, every total showing the lines that make it up, and an honest list of anything Claude could not read. Free account, on your phone, about ten minutes.
This is the win. One question, answered from your own numbers: where did it actually go.
Most people can name two or three of their categories and guess badly at the rest, and the guess is wrong in the same direction every time. Small, frequent spending is invisible because no single line stands out, and it adds up to more than the one purchase you do remember.
What makes the answer trustworthy is not the model, it is the guardrails. Every total has to show the lines that make it, and anything unreadable has to be quoted instead of guessed.
Categories that mean something anywhere
The prompt hands Claude a fixed list rather than letting it invent categories, because invented categories change between runs and then two months cannot be compared. Plain words that mean the same thing anywhere: housing, bills and utilities, groceries, eating out, transport, shopping, health, subscriptions, debt repayments, transfers to family, cash, income, and unclear.
"Unclear" is doing real work. A model with nowhere to put a line will force it somewhere, and a forced line is a wrong total.
One more distinction that quietly ruins months: money you moved between your own accounts is not spending. Counted as spending it appears twice, so the prompt lists it separately.
The prompt
In the same Incognito chat as your uploaded statement:
Sort this statement into categories.
Use only these categories: housing, bills and utilities, groceries, eating out, transport, shopping, health, subscriptions, debt repayments, transfers to family, cash, income, unclear. Do not invent a category. If a line does not clearly fit, put it in "unclear" rather than forcing it.
List separately, and do NOT count as spending: transfers between my own accounts.
For each category give me:
- the total
- every line that makes up that total, with its date, description and amount, so I can add them up myself
Then give me:
- the number of transaction lines you counted in total
- total money in and total money out
- an "unreadable" list: any line you could not read, quoted exactly as far as you can see it
Honesty rules, these matter more than the answer:
- Use only numbers that actually appear in the statement. Never invent a transaction.
- Never round a number to make a total work. If your totals do not reconcile, say so and show both figures.
You should see
A category by category breakdown where every total is followed by the lines that make it up, then a line count, money in, money out, a separate transfers list, and an unreadable list which may well be empty. Category totals with no lines under them means the prompt was ignored: ask for the lines. A total you cannot check is not worth having.
Now check it on paper. Take the biggest category, add its lines up on your phone calculator, and compare. Then count the lines on one page of the statement against the count Claude reported. Two minutes of checking is what makes this yours rather than something a machine told you.
Expect one or two lines to be wrong: a cash withdrawal that is really rent, a shop that could be groceries or household, a yearly payment landing in a month it does not belong to. Correct them by name and ask again: "the three lines from [name] are transport, not shopping. Recount both categories and show the arithmetic."
Do not fully trust the totals yet. A language model adding a column of forty numbers is a real failure mode, and a quiet one, because a wrong total looks exactly like a right one. Module 2 is about catching that, with one sentence you will end up appending to every money prompt you write.
Check it
- Every category total is followed by the individual lines that make it up
- You added one category up yourself and got the same answer
- The line count Claude reported matches what you count on the statement
- Transfers between your own accounts are listed separately, not counted as spending
- The reply is in your language and in the currency printed on the statement
If you see
The failure to watch for is outgoings that look far larger than a month you know was fine, because internal transfers got counted as spending. Reply "list every line you counted as a transfer between my own accounts, then recount total money out without them, showing the arithmetic". The other common one is silently dropped rows on a long statement. If the count is lower than yours, reply "number every transaction line from 1 to N in order, with its date and amount, before categorising anything" and run it again. Numbering first makes a missing row visible.
What you just learned
- A fixed category list plus an "unclear" bucket beats invented categories, which change between runs and make two months uncomparable.
- Every total must show the lines that make it, so you can check it yourself; a total you cannot check is not worth having.
- Transfers between your own accounts are not spending, and counting them is the commonest way a month looks worse than it was.
- Unreadable lines get quoted, never guessed.
Next: the one number in that breakdown you have been avoiding.
practice
Open Claude Cowork on your own computer and try this on real files. Each module ends with a checkpoint where you submit what you made.
Open in ClaudeNext
The uncomfortable number