I didn't use the Client Number line on the Status Sheet, so I put FINAL on that line before saving the file. 

Then I added the Client Number column to the Home Base for this year. When transferring returns, it is easy to sort the Client Number column to show the ones with only FINAL in the column and adjust accordingly when transferring next year's.

I also used the Client Number line for other things when necessary, like when I purchased a client list and could then sort Home Base to see which ones were still here,