Forecasting fight: Johns Creek debates $28M–$30M lost‑revenue scenarios and data accuracy

Johns Creek staff presented multiple lost‑revenue scenarios for FY2026 during the Aug. 11 work session, showing a plausible range from about $28.2 million to roughly $30.3 million depending on the period used for averaging and assumptions about reassessments and rollback rates.

Assistant City Manager Love explained that staff ran several scenarios (12‑month trend, two‑, three‑ and five‑year averages) and applied step‑down assumptions for loss distribution. "It's a calculated trend analysis based on current year actuals and historical scenarios," Love said, adding that staff typically round to the nearest $500,000 to account for monthly variance.

Bob urged caution, noting prior years when overly optimistic growth assumptions led to shortfalls. Several council members recommended building a statistical model (e.g., mean minus two standard deviations or segmented pre/post‑COVID analysis) to remove spikes that skew multi‑year averages. Chris suggested using probabilistic methods to better allocate capital funds.

Separately, staff disclosed a potential accounting error: a double‑counting between 'building residential' and 'building plan review' line items that could be about $1,500,000 too high in FY26 projections. Staff said they are reviewing permit transactional mapping and will incorporate corrections in the Aug. 25 packet and the midyear surplus conversation.

Council asked that staff refine the forecasting model, provide the documentation that underpins each scenario, and return with updated figures at the Aug. 25 work session.