Why a budget is not a spreadsheet exercise

In many companies the budget process looks the same: in the last quarter of the year, last year’s figures are taken, a growth rate is applied to each line, a few rounds of negotiation follow, and the result is approved. The file that comes out is technically a budget. But when the first variances appear in the second month of the year, it cannot answer one question: why?

Drivers, not numbers

A budget line is really the product of a few assumptions. Revenue is made of volume, average price and product mix. Payroll cost is made of headcount, average salary, benefits and hiring dates. Collections depend not only on sales but on how customers actually pay.

When the budget is built from these drivers, two things change. First, assumptions become explicit and open to discussion: instead of “sales will grow by 25 per cent”, the budget says “volume will grow by 10 per cent and price by 14 per cent”. Second, when actuals arrive, the variance can be decomposed: is the revenue gap coming from volume, price or mix?

Three statements, one set of assumptions

An income statement budget on its own is incomplete. When sales rise, receivables rise; when inventory policy changes, cash changes; buying equipment or a facility affects depreciation and the need for financing. If the income statement, balance sheet and cash flow are not tied to the same assumptions, a budget can be approved that is profitable on paper and unworkable in cash.

Every month, not once a year

A budget starts to age on the day it is approved. Under a rolling forecast, actuals are brought into the model every month and the rest of the year is re-forecast with current information. The budget stays fixed as management’s commitment; the forecast shows where the company is actually heading. The gap between the two is the real agenda for management.

A process, not a tool

This approach can be built in a spreadsheet or in dedicated planning software. What matters is not the tool but the structure: explicit assumptions, linked statements, and a model fed with actuals every month. When the budget stops being a file and becomes a management process, the finance function stops reporting the past and starts opening the future for discussion.

I show one implementation of this structure in the Budget & Forecast Management Model, and share the checklist I use when reviewing budget assumptions on the FP&A page.