Hello, Karen, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
HMRC have asked you to self assess for 13/14 so you must make a return. You have 30 days in which to do this to avoid penalties. You must declare the DOTAS scheme used in your return .
There is little more I can say at this stage, HMRC have put the ball in your court.
I do hope that you have found my reply of assistance.