I have a financial forecasting spreadsheet with the following values:

1. Forecast for the month
2. Actuals for the month
3. Variance

At the end of a one year period, I have total forecasted for the year, actuals spent for the year, variance and forecast to complete. This is the value I need help with.

The forecast to complete field needs to calculate the following:

We are in the month of August (month 8) and up until July we have actuals values populated within each month. Is there a formula which can add the forecast fields from August through to December considering the fact that actuals have been populated for all previous months?