Hi Dan – I don’t know what you meant by Planned Finish – is it Baseline Finish or Finish column but anyway I would state Planned Finish = Projected Finish = Finish column.
Project does not move the uncompleted work in the past to the future date and hence your Finish is incorrect. To reschedule the uncompleted work to be moved on or after 15th Jan, choose Project tab and click Update Project command. Select the second radio button “Reschedule uncompleted work …”, choose the date as 15 Jan, and set For “Entire Project”. This action will move the remaining work on or after Status Date and there by the Start and Finish date will be recalculated