> ## Documentation Index > Fetch the complete documentation index at: https://docs.budgetbandit.io/llms.txt > Use this file to discover all available pages before exploring further. # How zero-based budgeting works > Assign every dollar until there is nothing left to assign. The whole method in one page. Zero-based budgeting means you assign every dollar you have to a job before you spend it. You keep assigning until the money waiting to be assigned reaches zero. That is the entire method. It does not mean your bank account hits zero. It means none of your money is sitting around without a purpose. ## The one rule Every dollar gets a job. Income comes in. You hand it out to categories — rent, groceries, savings, debt — until [Ready to Assign](/concepts/ready-to-assign) reads \$0. Zero is the finish line. A dollar with no job is a dollar that disappears. Assigning it on purpose is how you keep it. ## How it works in practice You add an account balance, or income lands in a connected account. That money shows up in Ready to Assign with no job yet. You type amounts into categories until Ready to Assign reaches zero. Each category's Available amount is now real spending money set aside for that purpose. When you spend, the transaction comes out of a category. Its Available amount drops by what you spent. You always know how much is left for groceries because the number is right there. Plans change. Move money between categories when reality differs from the plan. See [Assign and move money](/budgeting/assign-and-move-money). ## What you can spend is the number in the category This is the part that separates zero-based budgeting from a forecast app. The amount you can spend on groceries is not last month's average and not a prediction. It is the dollars sitting in the Groceries category right now. When that number is $80, you have $80 of groceries left. When it is red, you spent money you had not assigned, and you need to cover it. ## Why budget only money you have You assign money that has already arrived, not money you expect. That keeps the budget honest — you are never spending a paycheck that has not landed. When new income comes in, you assign it then. For income that does not arrive on a steady schedule, see [Irregular income](/budgeting/irregular-income). ## Next The number at the top of your budget, and what it means when it is not zero. How to organize the jobs you give your dollars. What happens to leftover and overspent categories at month's end. Do it now, step by step.