The savings goal that exists as a number in someone's head is a wish. The savings goal attached to a concrete monthly surplus calculation — total income minus categorized fixed and dynamic expenses — is a plan. The gap between the two is the difference between financial drift and financial direction.
Fixed vs. Dynamic — The Stability Map
Fixed costs and Dynamic costs are the two structural categories that determine how the budget responds to life changes. Fixed costs — Rent, car insurance for both people, individual phone plans, Internet, Google Play, Car Repair Fund, Donations — are the commitments that don't flex month to month. They arrive at the same amount on the same date. The fixed total is the baseline: the number that the combined income has to exceed before discretionary spending is even possible.
Dynamic costs — Groceries, Fuel, Business Expenses, Clothing, Dining Out, Entertainment — are the variables that respond to decisions. Groceries spending varies by meal planning and shopping discipline. Fuel varies by driving distance and price. Dining out is a deliberate choice that can be reduced if the savings target is behind schedule. The categorization of dynamic costs by type means the month where the surplus is too thin reveals which specific category ran over, not just that the total was off.
Dual Income, Combined View
Colter's Income and Charlotte's Income with Child Benefit and Other income create the full household income picture. Total Income and Total Expenses are the two summary figures that produce the monthly surplus or deficit. In a dual-income household where both partners have individual expenses (separate car insurance, separate phone plans), the budget needs to reflect both the individual cost structure and the combined income reality. This template structure does exactly that — individual expense tracking within a combined income framework.
The Savings Calculation
Save per Week, Save per Month, and Save per Year are the three time-horizon views of the same surplus number. The monthly surplus tells you the month's performance. The weekly figure anchors the number to the spending decisions made in real time — a discretionary purchase that costs half a week's savings is a different framing than "it's only $80." The annual figure connects the monthly discipline to the year-end goal: the house deposit, the emergency fund threshold, the investment contribution target.
A budget that shows zero savings per month has failed before it started. The budget review that finds this and traces it back to a specific fixed commitment that has grown disproportionate, or a dynamic category that has normalized at a level the income doesn't support, is the review that produces a corrective action rather than a vague resolution.