Builds a zero-based monthly budget from take-home income using the 50/30/20 framework with explicit adaptation rules and sinking funds for irregular expenses. Use when someone says "help me make a budget", "I don't know where my money goes", "my spending feels out of control", or after an income change or move. Do NOT use for choosing what to fund first across debt, savings, and investing - use financial-planner instead; for sequencing multiple debts - use debt-payoff-planner; for sizing the cash cushion - use emergency-fund-planner; for company or campaign budget variance reporting - use budget-vs-actual instead.
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name: Budget Builder
description: Builds a zero-based monthly budget from take-home income using the 50/30/20 framework with explicit adaptation rules and sinking funds for irregular expenses. Use when someone says "help me make a budget", "I don't know where my money goes", "my spending feels out of control", or after an income change or move. Do NOT use for choosing what to fund first across debt, savings, and investing - use financial-planner instead; for sequencing multiple debts - use debt-payoff-planner; for sizing the cash cushion - use emergency-fund-planner; for company or campaign budget variance reporting - use budget-vs-actual instead.
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# Budget Builder
A budget is not a restriction on spending - it is a spending plan made in advance. The failure this skill prevents is the budget that dies in month two: built on gross income, blind to irregular expenses, and never reviewed. Build one that survives contact with real life.
## Operating procedure
### Step 1: Gather inputs
Collect before allocating anything. Label guesses as guesses.
1. Monthly take-home income - net dollars that land in the bank, all regular sources (salary, side income, rental). If income varies, use the average of the last three months and adjust upward only when a higher month is confirmed.
2. Fixed essentials with amounts: rent or mortgage, utilities, insurance, minimum debt payments, transportation to work.
3. Variable essentials: groceries, fuel, medical. Pull from 2-3 months of actual statements, not memory - self-reported spending typically undershoots reality by 10-20%.
4. Wants: dining out, subscriptions, hobbies, entertainment. Statements again, not memory.
5. Irregular annual costs: car registration, home repairs, holiday gifts, annual premiums, vet bills.
6. Savings and debt goals, ideally already prioritized by financial-planner.
### Step 2: Apply the 50/30/20 starting split
Allocate net income across three buckets as a starting point, not a rule:… install to load the full skill