What This Does

This playbook merges CSV exports from multiple bank accounts into a single, consistently formatted spreadsheet. Perfect for tracking all your transactions in one place or preparing data for budgeting apps.

Prerequisites

Claude Code installed and configured
CSV exports from your bank accounts
All CSVs in one folder

The CLAUDE.md Template

Copy this into a CLAUDE.md file in your bank statements folder:

# Bank CSV Merger

## Goal
Merge all bank CSV files into one unified CSV with consistent columns.

## Output Format
Date,Description,Amount,Category,Account,Original_File

## Column Mapping Rules
- Date: Look for columns named "Date", "Transaction Date", "Posted Date"
- Description: Look for "Description", "Memo", "Transaction", "Payee"
- Amount: Look for "Amount", "Debit", "Credit" (combine debit/credit into signed amount)
- For debit/credit: debits are negative, credits are positive

## Processing Rules
1. Read all .csv files in this folder
2. Detect the bank format based on column headers
3. Map columns to the standard output format
4. Add "Account" column with the source filename
5. Add "Original_File" for reference
6. Leave "Category" blank (for manual categorization later)
7. Sort by date (oldest first)
8. Output to "merged_transactions.csv"

## Skip
- Files starting with "merged_"
- Non-CSV files

Step-by-Step Setup

Step 1: Export your bank statements

Download CSV exports from each of your bank accounts. Most banks offer this in their transaction history.

Step 2: Create a folder for statements

mkdir ~/Documents/BankStatements

Move all your CSV files into this folder.

Step 3: Add the CLAUDE.md file

Create CLAUDE.md in the same folder with the template above.

Step 4: Run the merger

cd ~/Documents/BankStatements
claude "Merge all bank CSVs according to the CLAUDE.md rules"

Example

Input files:

chase_checking_jan.csv
bofa_savings_jan.csv
amex_credit_jan.csv

Output (merged_transactions.csv):

Date,Description,Amount,Category,Account,Original_File
2026-01-02,AMAZON.COM,-45.99,,Chase Checking,chase_checking_jan.csv
2026-01-03,PAYROLL DEPOSIT,2500.00,,Chase Checking,chase_checking_jan.csv
2026-01-03,TRANSFER TO SAVINGS,-500.00,,Chase Checking,chase_checking_jan.csv
2026-01-03,TRANSFER FROM CHECKING,500.00,,BofA Savings,bofa_savings_jan.csv
2026-01-05,WHOLE FOODS,-87.32,,Amex Credit,amex_credit_jan.csv

Tips & Variations

Add auto-categorization: Extend the rules to automatically categorize transactions (e.g., "AMAZON" → "Shopping")
Monthly folders: Create a folder structure like 2026/01/ and process by month
Different output formats: Modify to output Excel (.xlsx) or for specific apps like YNAB or Mint

Troubleshooting

Problem: Dates are in wrong format

Solution: Add specific date format rules to CLAUDE.md for each bank (e.g., "Chase uses MM/DD/YYYY")

Problem: Amounts are all positive

Solution: Check if your bank uses separate Debit/Credit columns and update the mapping rules.

Problem: Missing transactions

Solution: Make sure all CSV files are properly downloaded and not truncated. Some banks limit export rows.

Bank Statement CSV Merger