If the seasonal index is 1.00, that indicates:

A seasonal index of 1.00 indicates that the actual sales are exactly at the trend estimate for that particular period. This index is a measure of how much actual values deviate from a trend line, reflecting seasonal fluctuations. When the index is at 1.00, it signifies that the sales figures are neither above nor below what the long-term trend would predict—they are perfectly aligned with what is expected based on past data trends.

In contrast, if the seasonal index were greater than 1.00, it would indicate that sales are performing better than the trend suggests, while an index less than 1.00 would reflect weaker performance relative to the trend. Thus, a seasonal index of 1.00 specifically captures the point of equilibrium between actual sales and trend forecasts.