The 'Include taxable saving in Planned Saving column' setting can be found within the Gear Icon > Settings > Methodology tab of each client plan:
This setting can be used to move taxable savings from the Net Flows column, to the Planned Savings column of the Retirement > Cash Flows > Summary page. This is a purely visual change, and will only appear as a setting when using Modified cash flow based as your Planning method. By default, this setting is unchecked.