A Personal Finance Glossary for Budgeting

Net Income

The amount of money you take home after taxes and other payroll deductions — such as Social Security, Medicare, and any employer-sponsored benefits premiums — have been subtracted from your gross pay. Net income is the figure you should use as the basis for your budget.

Gross Income

Your total earnings before any deductions are taken out. Gross income is what appears at the top of a pay stub, but it overstates what you actually have available to spend, save, or invest.

Fixed Expenses

Costs that stay the same from month to month, such as rent or mortgage payments, car loan payments, and insurance premiums. Because fixed expenses don't fluctuate, they're typically the first items entered into a budget.

Variable Expenses

Costs that change in amount each month, such as groceries, utilities, and gas. Variable expenses require estimation and are often the category with the most room for adjustment.

Discretionary Spending

Money spent on non-essential wants — dining out, entertainment, subscriptions, and hobbies. Discretionary spending is distinct from needs and is usually the first area reviewed when a budget needs trimming.

Emergency Fund

A dedicated pool of savings set aside exclusively for unexpected expenses, such as a medical bill, car repair, or job loss. Financial educators commonly recommend maintaining three to six months of essential living expenses in an emergency fund, though the right amount varies by individual circumstances.

Sinking Fund

A savings pool built up gradually for a known, planned future expense — such as an annual insurance premium, holiday gifts, or a car replacement. Unlike an emergency fund, a sinking fund targets a predictable cost and is spent intentionally when that cost arrives.

Zero-Based Budget

A budgeting method in which every dollar of net income is assigned a purpose — spending, saving, or debt repayment — so that income minus all allocations equals zero. The goal is intentionality, not spending everything.

Debt Avalanche

A debt repayment strategy that directs extra payments toward the balance with the highest interest rate first while making minimum payments on all others. This approach minimises the total interest paid over time.

Debt Snowball

A debt repayment strategy that targets the smallest balance first while making minimum payments on larger debts. Paying off smaller debts quickly can provide motivational momentum, even if the total interest paid may be higher than with the avalanche method.

Budget Deficit

The shortfall that occurs when your total expenses exceed your net income in a given period. Identifying a deficit is the first step toward correcting it — either by reducing spending, increasing income, or both.

Budget Surplus

The amount remaining when your net income exceeds your total expenses for a given period. A surplus can be directed toward savings goals, debt repayment, or investment — making it one of the most important outcomes a budget can produce.