arganoid Gillett

"Total loss to carry forward after all other set-offs including unused losses brought forward" I have never entered anything in this box before despite having made a loss on my second business for the last few years, but I may end up making a profit in the next year or two. Is it necessary to fill in this box to be able to offset the loss against future profits? Should I enter this year's loss plus the losses from the previous three years? I am using cash basis.