Is there a way to submit the client Rep form without filing his return or start to filing his return.
Thank you
If you are referring the the Authrep form, you don’t have to file the return. Just fill in the name and SIN# on the Authrep form (info screen), have the client sign and then transmit.
From Your previous posts… you are most likely talking about a corp… Please have them sign the consent, upload to CRA… they will have to login into their My CRA business Account and accept you.
Thank you for sharing the knowledge, 
How about the individual client please
Unclear exactly what your question is.
If it is how to obtain consent, CRA website has all the answers for how to obtain consent.
One way is having client access their My account and have them authorize you with your Rep ID.
The other way is to start a tax client file in Taxcycle and have client sign Auth Rep and you submit electronically.
I often create in this year for work to be done in past years.