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Budget modelling

Try the template

One template for costs and one for revenues, the same every edition. This is its core, taken from the real sheet: change the numbers.

  • What it is. A simplified version of two sheets of the real template: C-BUDGET for costs and R-BUDGET for revenues. The original is an Excel workbook, so the layout here is of course different: each row of the sheet becomes a card, and only the columns that carry the reasoning are kept.
  • The logic. Planned is quantity × net unit price, multiplied by the prudence factor: λ on costs, 1 or above; π on revenues, between 0 and 1. Actual is quantity × net unit price, filled in after the edition.
  • How to read it. On the line, ○ is the plan, ◆ the plan with prudence, ● the actual: the closer ◆ sits to ●, the better the prudence worked. The bars split the variance into quantity (more or fewer units) and price (a different unit price), and the two always add up. Change any number or move the slider: everything updates.

λ raises a cost, and only where the estimate tends to run low. The total comes out with and without it, so after the edition you can see whether it helped.

Venue rent

Venue & occupancyEVENT
Planned
×=€90,000
λ
1.10→€99,000
Actual
×=€95,000
quantity€0price+€5,000variance+€5,000
✓ quantity + price = varianceprudence helped: yesλ that was needed: 1.06

Backdrop 2×2

Graphics & signageSPONSOR
Planned
×=€2,400
λ
1.00→€2,400
Actual
×=€3,300
quantity+€600price+€300variance+€900
✓ quantity + price = varianceprudence helped: not setλ that was needed: 1.38
Planned€92,400
planned with λ€101,400
Actual€98,300
error without prudence+€5,900
error with λ−€3,100

π cuts a revenue, between 0 and 1: on revenues the usual error is optimism, not a low quote. The sheet accepts nothing above 1.

Gold sponsor, Italy

Sponsorship packageEVENT
Planned
×=€20,000
π
0.90→€18,000
Actual
×=€18,000
quantity€0price−€2,000variance−€2,000
✓ quantity + price = varianceprudence helped: yesπ that was needed: 0.90

Gold sponsor, abroad

Sponsorship packageEVENT
Planned
×=€15,000
π
0.80→€12,000
Actual
×=€15,000
quantity€0price€0variance€0
✓ quantity + price = varianceprudence helped: noπ that was needed: 1.00

Early bird tickets

Ticketing, general admissionEVENT
Planned
×=€10,000
π
1.00→€10,000
Actual
×=€8,100
quantity−€1,000price−€900variance−€1,900
✓ quantity + price = varianceprudence helped: not setπ that was needed: 0.81
Planned€45,000
planned with π€40,000
Actual€41,100
error without prudence−€3,900
error with π+€1,100

Fig. 1. Planned is last year’s actual, split into quantity × net unit price, then the prudence factor. Every variance splits into a quantity effect and a price effect, and the two always add up.

Source: MBW budget template and its compilation guide; the rows are the guide’s own examples · Method: the sheet’s formulas, column by column · Limit: a simplified view. The real sheets add status, invoices, VAT, accruals and the accounting account.

Four budgets, four formats

Before building anything, I read the four budgets already in use, line by line. No two were built the same way.

FormatLinesVATCategoriesActualsTotal
2023Notion27not declarednonenone€137,976
2024Excel13 blocksincluded13column, never filled€183,640, 4 blocks left out
2025Notion23ambiguousnonenone€88,634
2026Notion43net and VAT apart14, but 17% unreadablenone€113,177
Templateone workbookone line per itemalways net, VAT in its column13 closed, plus who it is foron every line, next to the planreconciled three ways

Fig. 2. The four budgets against the same questions, and the template at the bottom.

Source: the 2023 to 2026 budgets, exported from Notion and Excel · Method: each file read line by line; the 2024 total rebuilt from its lines · Limit: budgets are plans, not accounts.

planned in the budgetspent, from the accounts
  • 2023 · +36%
    €138k
    €188k
  • 2024 · +49%
    €217k
    €322k
  • 2025 · +53%
    €89k
    €136k
  • 2026 H1 · +11%
    €113k
    €126k

Fig. 3. Every year the company spent more than its budget planned, always in the same direction. That is what λ is for.

Source: the four budgets; filed accounts FY2023 to FY2025, interim accounts at 30 June 2026 · Method: planned total (2024 rebuilt from its lines) against production costs · Limit: not a variance. The budget covers the event, the accounts the whole company.

  • 9 of 13blocks added up by the 2024 total. Three subtotals summed the wrong range
  • €33,055missing from that total, 18%. It was the break-even threshold in use

Built to be checked, left to be used

Seven sheets: two to fill in, two that add up and check, one that crosses costs and revenues.

you fill inC-BUDGETcosts: one line per item, planned and actual
adds up and checksSUMMARY-Cby category, recipient, status and account, with the checks to read before sending it
you fill inR-BUDGETrevenues: contracts, ticket waves, forecasts
adds up and checksSUMMARY-Rthe same, plus fiscal year and cash collected
crosses the twoMARGINEthe edition’s margin, edition against structure, and the margin of each sponsor, a question that had no answer
Liste the drop-down listsLegenda the guide, inside the file

Fig. 4. How the workbook moves: what is written on the left is read, summed and checked on the right.

Source: MBW_budget_template.xlsx · Method: the sheets and what each one reads · Limit: the map from accounting account to budget category is still waiting for the firm’s approval.

  • 43 of 43lines of the 2026 budget land in a category, €100,584 net. Before, 17.2% could not be summed
  • 86.6%of €633,966 of costs in three filed years fall on the twelve event categories, the rest on the admin residual. No account is left out
  • 24 of 24functional tests passed on the workbook: summaries, reconciliations, margin chain
  • 2 × 1 pagerulebooks left with the firm, costs and revenues: fill it in by hand, or hand it to the AI agents

The firm has adopted it. One step is left, and it is theirs: approving which account belongs to which budget category.

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