Budgeting

Choose a time period

Most personal budgets use a monthly period, but pay schedules and expenses may be weekly, biweekly, quarterly, or annual. Convert everything to a common period.

A biweekly pay schedule has $26$ pays per year, not exactly two per month.

Net income

Budget with money actually available after deductions:

Variable income should be estimated conservatively using a documented average or base amount.

Expense categories

• Fixed: similar amount and due date, such as rent.
• Variable: changes with use, such as groceries.
• Periodic: occurs irregularly, such as annual fees.
• Discretionary: flexible wants.

Categories help plan, but every expense still belongs to the same total cash flow.

Worked example: monthly cash flow

The budget balances, but the small buffer may need strengthening for irregular costs.

Common mistakes

Using gross rather than net income. Budget only spendable money.

Forgetting annual or irregular expenses. Use sinking funds.

Making the plan total exactly to income with no buffer. Small surprises then create debt.

Treating savings as whatever remains. Give it a planned category when possible.

Using a template percentage as a moral judgment. Adapt to real constraints and priorities.

Quick self-check

• Are income and every expense converted to the same period?
• Is income net and conservatively estimated?
• Are fixed, variable, periodic, debt, saving, and flexible costs included?
• Is there a buffer and plan for emergencies?
• Do actual-versus-planned results lead to revisions?
• Are goals, interest rates, deadlines, and tradeoffs explicit?