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Add up my receipts and tell me where the money went

Paste receipts, a card export, a pile of numbers. Get totals that add up.

SKILL.md

spending-summaryThe whole skill. Nothing else to fill in.
---
name: spending-summary
description: Totals receipts, card exports or expense lists into categories and flags what looks odd. Use when the user pastes receipts, a bank statement or expenses and asks where the money went or to add it up.
---

# Where the money went

Add it up so the total can be checked, and never guess a line.

## Steps

1. Read every line into three parts: what it was, how much, and when. Keep the merchant name as written.
2. Any line you can't read confidently goes into a list called "Couldn't read", with the raw text copied in. Never drop it and never guess at it.
3. Group the rest into categories that suit what's actually there, not a standard chart of accounts. Six or seven categories at most.
4. Under each category, list its lines, then the category total. The categories must sum to the grand total, and the grand total must equal the sum of every readable line. Show that check.
5. Flag anything worth a second look: a charge much larger than the others in its category, the same merchant twice on one day, a subscription that's gone up.

## Rules

- Never invent a merchant, an amount, a date or a category. An ambiguous line goes to "Couldn't read" or gets one short question.
- Use the currency in the input. Never convert, and never mix two currencies into one total. If there are two, give two totals.
- Round only at the very end, and say if you did.
- Don't advise unless asked. "You spent £212 on takeaways" is the job. "You should cook more" is not.

## Output

A table of categories with totals, then the lines under each, then the arithmetic check, then "Couldn't read", then anything flagged. Currency symbol on every figure.

Where it goes

Claude Code: save the file as ~/.claude/skills/spending-summary/SKILL.md. The folder name has to match, and a new session picks it up.

claude.ai: turn on code execution in Settings → Capabilities, then go to Customize → Skills and upload the zip. The zip already has the folder at its root, which is what that upload wants.

When it fires

Claude decides by reading one line, the description at the top of the file. This one says: Totals receipts, card exports or expense lists into categories and flags what looks odd. Use when the user pastes receipts, a bank statement or expenses and asks where the money went or to add it up.

The instruction that does the work

Making the arithmetic checkable. A summary that just states totals is a summary you can't trust, and adding up other people's numbers is exactly what models are worst at. Every category shows its lines and the totals have to reconcile, so a mistake shows up as a mismatch instead of a plausible number.

Why unreadable lines get their own list

A smudged receipt or a truncated CSV row is normal. The dangerous behaviour is a model filling it in from context. The list is short, it's yours to fix, and nothing vanishes into a total.

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