Calculate category and surplus variances using consistent periods and definitions.
Propose a specific next-month correction tied to a cause and state what requires checking.
What actually changed, and what should change in the plan?
A monthly budget is a forecast to test, not a promise that reality will match every entry. At month-end, collect payments that actually occurred over the same period as the plan. For each category write actual minus planned. A positive expense variance means more was spent than expected; a negative one means less. Calculate surplus variance as actual surplus minus planned surplus, so it falls when spending rises and income is unchanged. Keep the category definition stable. If grocery purchases count as food this month, do not move them to miscellaneous next month just to make the food line look better. Separate payments leaving the household from transfers into a savings account it still owns. This table includes goal saving in planned use because it reserves money from spendable surplus; do not mistake it for consumption or a loss of household net resources. When income is irregular, compare actual and planned receipts too before attributing every surplus change to spending.
A variance tells you where to investigate, not why it occurred. Higher food spending could reflect a price rise, visitors, or meals omitted from the original plan. Check receipts and frequency before selecting a remedy. Record a one-time event and fund it if known; do not automatically raise every future monthly target because of it. A recurring change or a line persistently below realistic need calls for a revised baseline or buying method. Distinguish reliable improvement from chance as well. If transport is 40 lower because one trip was cancelled, do not assume the reduction will persist. A useful correction is observable: for example, test a food ceiling of 1,000 next month and check receipts halfway through, rather than simply saying 'spend less'. If an unavoidable need makes the ceiling unrealistic, revise it openly and identify the funding source instead of hiding the difference in another category.
Do not give expense and surplus variances the same sign. If use rises 200 and income stays constant, the use variance is +200 but the surplus variance is −200. Check with two equations: income minus use equals surplus, once for the plan and once for reality. If category variances do not sum to the change in total use, a row is missing, counted twice or classified differently. For a periodic charge such as an annual fee, return to its monthly provision rather than calling the whole payment month a surprise; in the cash calendar, still show the real payment date. A major life event may change priorities, so the monthly review should not become a device for blaming a household for a real need. Its purpose is to find an assumption that no longer holds and specify a decision that can be checked. Record the review date and the entry to revisit; otherwise the notes may never affect the next cycle's budget.
Lesson summary
Expense variance is actual minus planned; higher use at unchanged income yields a negative surplus variance. Receipts and repetition help explain the difference before revising the next baseline or setting a trackable action.
