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- Budgeting & Forecasting
- Features
- Drivers and assumptions
Drivers and assumptions
Drivers and assumptions connects business inputs to the financial plan. Drivers define values such as headcount, average salary, rent and sales growth. Driver values keep the inputs for a particular version, entity, period and scenario. Driver formulas explain how those inputs become budget lines. Finance can discuss the reason behind a number instead of comparing unexplained spreadsheet totals, while the calculation basis preserves the inputs and rules used for the reviewed plan.
OverviewAssumptions History×
Budgeting & Forecasting · Drivers and assumptions
New
Assumptions History
Assumptions log
| Log number | Change type | Driver | From value | To value | Changed by | |
|---|---|---|---|---|---|---|
| AL-19091 | Driver created | Emmanuel Boateng | 8.0% annual growth | 6.5% annual growth | Oliver Grant | |
| AL-47003 | Driver updated | Pavel Novak | $120,000 monthly spend | $135,000 monthly spend | Lena Fischer | |
| AL-80046 | Driver value updated | Sofia Haddad | 45 new hires | 38 new hires | Jun Seo | |
| AL-88406 | Formula created | Jun Seo | 12 week lead time | 14 week lead time | Oliver Grant | |
| AL-65984 | Formula updated | Pavel Novak | $6.80 freight per unit | $7.40 freight per unit | Jun Seo |
6 of 6 records
8.0% annual growthAssumptions log · AL-19091
Driver createdDriverEmmanuel Boateng
To value6.5% annual growth
Changed byOliver Grant
Changed at14 Oct
What you can do
Define the inputs with their owners
A driver needs a clear unit, source and responsible owner. Headcount is a count; salary is a currency amount; a benefit load is a percentage. HR, payroll and sales forecasts may supply inputs under the configured contracts, while a department can propose a manual change within its permitted scope. Imported values remain planning inputs and do not authorize a hire, compensation change or sales commitment. Retain the source date and effective basis before using an input in a submission.
Calculate against one explicit basis
Resolve each formula against the intended budget version, Scenario, Entity and Period. Use the validated driver CODE and formula CODE grammar and check the dependency graph before publishing results. A missing input or cycle returns a clear finding and leaves the last published snapshot intact. Where an override is permitted, keep the computed value beside the entered amount and its explanation. A new master default or formula revision must not recalculate a plan that has already been approved.
Make changes explainable after review
Assumptions History connects a recorded change to its driver, formula, version, author and reason. Mid-cycle master changes require the configured Admin decision and a new retained basis. Compare the prior and new inputs before submitting the affected draft again. Approved plans, scenario runs and board packs continue to reference the earlier calculation basis when appropriate. An audit entry must retain the actual source values; a timestamp alone cannot explain why a formula produced a different result.
What your team sees
- Assumptions History. Open the related work within your assigned scope.
Rollout checks
Start with a personnel-cost formula and a facilities-cost formula. Include a missing value, an invalid dependency cycle, a manual override and a rate change after approval. Reconcile the resulting monthly amounts to the retained input basis. Verify that a failed calculation publishes no partial output and that a retry retains the same calculation identity.
What it keeps track of
Data model- Drivers
- Input drivers used by formulas — Headcount, avg salary, rent per SF, sales growth pct, benefit load pct, billable utilization pct. Catalog + default values; per-Entity per-Period values live in driver values.
- Driver values
- Per Driver per Entity per Period the actual numeric value used by formulas. The grain mirrors budget lines so a Headcount value for
(Engineering, 2026-03-01)resolves cleanly into the Personnel Expense formula for the same cell. - Driver formulas
- Formula definitions referencing Drivers and other driver formulas. Resolved at computation time per
(Version, Entity, Period, Scenario)cell; output writes a budget lines row ofType: Budget(or Forecast). Driver dependency tracing is performed at workflow #4 (driver-update-cascade) evaluation time using one validated expression grammar:Drivers.CODEandFormulas.CODEidentifiers. Validate dependencies and reject cycles before publishing any affected cells. A failed computation leaves the last published snapshot intact and reports cycle detected to FP&A Analyst. There is no separate dependency-graph table. - Budget lines
- The atomic line of the plan. Each cell keeps its version, period, account, entity and scenario. Budget cells are unique within that basis. Forecast cells additionally require rolling forecast and snapshot key; Actual cells require a reconciled ledger snapshot key. A comparison names its chosen bases explicitly instead of joining ambiguous latest rows. Published snapshots and locked plan amounts are immutable.
- Assumptions log
- Audit trail of every Driver, driver value, and driver formula change plus every budget transfer apply. The auditor’s source of truth for “what assumption produced what number when.”
- Budget account settings
- Per-Account (optionally per-Entity) thresholds that drive variance materiality flagging and flux-comment requirements. Read by the
variance-recomputeworkflow at evaluation time.
Who uses it
Permissions- Admin
- Maintains approved masters.
- FP&A Director
- Owns planning formulas and review.
- FP&A Analyst
- Prepares scoped draft inputs.
- Cost-Center Head
- And Manager contribute only within their permitted entity and input categories.
Set up Budgeting & Forecasting your way.
Start free, then use Proto to change fields, steps and approvals before your team goes live.