How to build a budget with Claude from your real transactions

1. Connect your bank to Claude

Claude needs to see your transactions. Sign up at bankbridge.money, link your checking account and every credit card you spend on, then add BankBridge to Claude:

• Claude.ai, Desktop, or mobile: add a custom connector with the URL https://bankbridge.money/api/mcp and sign in. See the Claude.ai setup page.
• Claude Code: install the plugin, which includes the /budget-draft command used below. See the Claude Code setup page.

Connect the credit cards. If you budget from checking alone, every card payment shows up as one large lump and you lose the detail of what you bought.

2. Pull a three-month baseline

Start from what you spent, not what you hope to spend. Ask:

“Summarize my spending by category for each of the last three full months, then give me the three-month average per category. Exclude credit card payments and transfers between my own accounts.”

Claude calls get_spending_summary once per month with the category grouping. Read the result before moving on. If one month had a one-off (a flight, a car repair), say so and ask Claude to show the average with and without it.

The exclusion in that prompt matters. Card payments from checking and the purchases on the card describe the same money. Counting both inflates your spending. More on this in stop double-counting credit card payments.

3. Separate fixed bills from flexible spending

A budget has two parts: bills you will pay regardless, and spending you can adjust. Ask:

“List my recurring charges with their monthly amount. Then list my flexible categories separately.”

Claude uses get_recurring_charges, which detects repeating charges by merchant and cadence. Check two things in the result:

• Rent paid by transfer. If you pay rent with a bank transfer or a payment app, it may be labeled as a transfer. Tell Claude which transfer is rent so it counts as a bill. See transfers that count as spending.
• Annual and quarterly bills. Insurance, domain renewals, and memberships hit once or a few times a year. Ask Claude to look back twelve months for these and convert them to a monthly amount.

4. Set caps and a savings target

Now turn the baseline into a plan. In Claude Code, run:

/budget-draft

The command averages three months by category, lists recurring charges as fixed, pulls your average monthly income from get_monthly_cashflow, and proposes a cap for each flexible category. Discretionary categories get a cap about 10% under the average; essentials stay at the average. Any category that would need more than a 30% cut is flagged for you to decide instead of being cut automatically. The output ends with income minus fixed bills minus caps: your savings target.

In the Claude apps, pick the same prompt from the + menu, or ask in your own words:

“Draft a monthly budget: fixed bills, a cap for each flexible category about 10% below my three-month average, my average income, and what is left to save. Flag any cap that needs a cut larger than 30%.”

Then edit it in conversation. “Keep groceries at the average, take the difference out of restaurants” works.

5. Save the budget where Claude can find it

BankBridge does not store anything, and a new chat starts without the old one. Put the final budget somewhere persistent:

• Claude.ai: create a Project called Budget and paste the table into its instructions. Every chat in the project starts with it.
• Claude Code: ask Claude to write it to budget.md in a folder you use for personal finance.

6. Check it every month

A budget you never compare against is a wish list. At the start of each month, ask:

“Compare last month's spending by category to my budget. Show over and under for each, and the three biggest charges in any category that went over.”

In Claude Code, /compare-months and /monthly-check give you the month-over-month view and a one-page report. If you are consistently over in one category for three months, the cap is wrong, not you. Raise it and take the difference from somewhere else.