Bank Statement CSV Merger
Combine multiple bank statement CSV files into one unified spreadsheet with consistent formatting.
You have bank statements from 4 different accounts and each one exports CSVs with different column names, date formats, and layouts. Manually combining them in Excel takes an afternoon every month.
Who it's for: freelancers tracking income across multiple accounts, small business owners doing their own bookkeeping, accountants consolidating client statements, couples merging household finances, tax preparers gathering annual data
Example
"Merge these 12 bank CSV files into one spreadsheet" → All transactions unified with consistent date format, standardized categories, duplicate detection, and running balance — ready for your budgeting app or accountant
New here? 3-minute setup guide → | Already set up? Copy the template below.
# 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
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
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.csvbofa_savings_jan.csvamex_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.