Drivers and formulas

A driver describes an expected receipt or payment: its amount or formula, cadence, effective dates, and accounting template. Confirmed drivers create balanced projected entries; the driver itself is not a posted actual.

Fixed and formula amounts

Fixed drivers use an explicit amount. Formula drivers derive the amount from named model variables and dimensions for each applicable month. Cadence still determines which months produce entries.

For example, named inputs for headcount and monthly cost per person can feed payroll. If payroll has department dimensions, a driver can use sum(payroll) to reduce the result to a monthly total.

Formula amounts are in major currency units and converted through the deterministic engine to minor-unit journal values. A displayed fallback amount is not the formula’s authoritative output.

Formula language

The model uses a bounded parser, not arbitrary JavaScript. Supported expressions include arithmetic, parentheses, variable references, dimension selectors, reductions such as sum and avg, and functions such as prev and round.

headcount * monthly_cost
sum(payroll)
payroll[department=engineering]

These examples assume the named variables, dimension and item already exist in the company model. A driver result must reduce any remaining dimensions to a single amount for each month.

Dated inputs continue from their effective month until replaced by a later input for the same coordinates. Missing inputs may evaluate to zero with validation warnings; review completeness rather than assuming zero means confirmed absence.

Review validation

Unknown variables, invalid dimensions, circular dependencies, invalid function arguments and evaluation failures need correction. Negative or invalid amounts cannot silently produce ordinary positive cash drivers. Model and formula size limits bound evaluation.

An exception is visible in the forecast. It should not be “fixed” by typing a convenient cash result over the output.

Change an assumption

Inspect the driver, model inputs and accounting template. Use scenario changes when comparing alternatives before approval. Review the downstream cash effects and constraints in /goal-decisions.

Changing a source driver does not rewrite preserved expectations. A recurring capture approval may become stale; use Recurring assumptions and recovery for the reviewed replacement path.

Formula-based recognition is outside the bounded recognition workflow. See Accounting and recognition.