Accounting _Ver02. _Rolling Forecast -Why Budgets “Die the Moment They Are Created”- and How Companies Can Finally See Their Future Numbers

Shigenori Tanaka
3月1日
読了時間: 2分

更新日：5月14日

2026/03/01

Hello everyone.

Today's topic is the Rolling Forecast, a tool widely used in Western companies but still underutilized in many Japanese mid-sized manufacturers.

Why do budgets become useless so quickly?

In many companies, the annual budget becomes irrelevant within three months.

Market fluctuations
Cost changes
Employee turnover
Project delays
Equipment downtime

The reality on the shop floor keeps changing, but the numbers do not.

As a result, management meetings turn into endless “variance analysis” sessions—essentially, post-mortems of the past. But what management truly wants to know is:　

“What will happen next?”

What is a Rolling Forecast?

A Rolling Forecast is a continuously updated forward-looking projection, commonly used in Western companies as a bridge between budget and actuals.

It means updating the next 12 months (or 6 months) every single month.

The budget stays fixed
The forecast is updated monthly

Separating these two allows management to make decisions based on future numbers, not outdated assumptions.

Why is it difficult for mid-sized companies to implement?

The reason is simple:

The underlying data for forecasting does not match across departments.

Shop floor → Actual labor hours, outsourcing, materials
Accounting → Financial accounting numbers
Management → Future-oriented numbers

If these three are not aligned, a Rolling Forecast will never function.

Three steps to make Rolling Forecast work

Step 1: Build “One Truth”

As explained in the previous article:

During the period: Standard rate × actual labor hours
At period-end: Actual rate × labor hours + project-level provisions

This aligns the numbers used by operations, accounting, and management.

A Rolling Forecast cannot exist without this foundation.

Step 2: Convert future drivers into numbers

Future changes must be translated into labor hours, rates, and quantities:

Project progress
Changes in outsourcing costs
Material price fluctuations
Hiring and turnover
Equipment utilization

Only when these drivers are quantified can future numbers be created.

Step 3: Update the next 12 months every month

After each monthly closing:

Reflect actuals

Review future assumptions
Update each project
Adjust for cost changes

This ensures the company always has an updated 12‑month forward view.

For example, after three months have passed, you create a 3+9 forecast: 3 months of actuals + 9 months of forecast. The next month becomes 4+8, and so on.

Conclusion: Budgets are the past. Forecasts are the future.

The budget is a commitment
The forecast is reality

Management should focus on future numbers, not outdated budgets.

A Rolling Forecast only works when financial accounting, management accounting, and shop-floor data are fully integrated.

This system can only be designed by someone who understands:

Manufacturing operations
Financial accounting
Management accounting
Project accounting

In Western companies, 8+4 or 9+3 forecasts are often used as the basis for next year's budget. This requires highly accurate year-end landing estimates as the fiscal year approaches.

If you want to build a Rolling Forecast for your company

The optimal design differs for every company: