VA Fast Letter 13-13 is very informative for those who have questions about TDIU. Read the rest at the link: Overview of Changes VA will no longer presume a claim for TDIU is a claim for increase in all service- connected disabilities. As part of a substantially complete application for TDIU, VA will require that the claimant with multiple service-connected disabilities specify at least one disability that he or she believes causes the unemployability. VA will consider the Veteran’s