This report claries an issue involved in performing seasonal adjustment with growth rates. Specifically, we consider the effect of including or excluding trading day regressors in the seasonaladjustment routine. This work provides insight to X-12-ARIMA (or its successor X-13ARIMA-SEATS) users who wish to calculate a 12-month concatenated growth rate or any other derived function at some point before, during, or after seasonal adjustment. This may be a delicate issue since the operation of calculating an annual (or concatenated annual) growth rate can remove seasonality, but does not remove trading day effects.