Paula
What you have been told is completely wrong, although it is very likely that your son will have to have a face to face assessment.
The criteria for PIP is fundamentally different from DLA, even if the information you used for his 2014 DLA award was used in regard to his PIP claim, it may not actually result in an award.
Our advice is to submit supporting evidence with his PIP claim, that way you know what has been made available and you can integrate it into your answer on the PI claim form.
Have a look at our PIP Claim guide for details of the process and the criteria you will need to go through when invited to claim.
www.benefitsandwork.co.uk/help-for-claimants/pip Gordon
