How to Build an Expense Budget Monitor

Budgets in spreadsheets are checked at the end of the month, when it's too late. Link expenses to categories and watch the remaining budget live.

1. Create Budget Categories with a monthly limit, and link each Expense to a category.
2. Add a Rollup on categories that sums this month's expenses.
3. Add a rule: "remaining = limit minus spent", plus a status of OK, Close or Over.
4. Add a bar chart view of spent versus limit by category.