Last month, the company expected to finish the year with $12 million in operating profit.
This month, the forecast says $10.8 million.
The CFO asks what changed.
Finance produces a report showing that revenue is down, labor costs are up, and several departments have revised their spending assumptions.
All useful information.
But does it explain the $1.2 million movement?
Not necessarily.
A forecast-to-forecast bridge should reconcile the previous forecast to the current forecast, separating actual results, changes in business assumptions, timing differences, and management decisions.
The purpose is to explain why the financial outlook changed since the last forecast was approved.
That sounds straightforward until the company starts comparing different periods, replacing forecast months with actuals, and treating every department’s latest estimate as though it represents new information.
A good bridge gives leadership a clear explanation of what changed and whether anything needs to be done about it.
Before presenting one, FP&A should make six checks.
1. Are You Comparing the Same Financial Period?
A rolling forecast changes its time horizon as the business moves forward.
That creates a problem when finance compares two versions without checking which periods each one includes.
Suppose the September forecast covers October through the following September.
The October forecast covers November through the following October.
Comparing the two totals directly introduces a different month at each end.
Even if every overlapping monthly assumption remains unchanged, the totals may differ.
That isn’t necessarily a change in the underlying business outlook.
It’s partly a change in the reporting window.
Finance should choose a consistent comparison period.
For example, when explaining changes to the current fiscal-year outlook, compare the same January-through-December period in both forecast versions.
When explaining the next twelve months, use a common twelve-month window or separately disclose the effect of rolling the horizon forward.
The decision rule is simple:
If the periods aren’t identical, isolate the calendar effect before attributing the difference to business performance.
Otherwise, a forecast bridge can manufacture a variance simply because time passed.
Which is an unusually expensive way to discover how calendars work.
2. Have You Separated Actualization From Changes in Future Assumptions?
Every forecast refresh introduces new actual results.
Those actuals replace estimates that were included in the previous forecast.
That movement should be distinguished from changes in the remaining forecast months.
Suppose the previous full-year operating profit forecast was $12 million.
October was expected to generate $900,000 in operating profit.