Use the following formula to help you stay on budget. Take your monthly income after taxes and 401(k) contributions and prioritize spending as follows:
• 50 percent for fixed costs like rent, utilities and monthly subscriptions.
• 20 percent toward building a financial foundation, like house payments, paying down student loans or just investing in an emergency savings fund (more on this later).
• 30 percent into flexible spending, which is day-to-day expenses like groceries, eating out, entertainment and gas.