Department of Veterans Affairs Post-Traumatic Stress Disorder Processing Claims Improvement Act of 2021 This bill requires the Veterans Benefits Administration (VBA) within the Department of Veterans Affairs (VA) to update an ongoing national training program for claims processors who review compensation claims for service-connected post-traumatic stress disorder (PTSD). Such claims processors will be required to participate in the training at least once a year starting in their second year of being a VA claims processor. The training program must be standardized at regional offices of the VBA and include instruction on stressor development and verification. The VBA must establish a formal process to annually analyze training needs based on identified processing error trends. Additionally, the VBA must establish a formal process to conduct annual studies to help guide the national training program for claims processors. Finally, the VBA must evaluate the guidance relating to PTSD to determine if updates are warranted to provide claims processors with better resources regarding best practices for claims processing, including specific guidance regarding development of claims involving compensation for service-connected PTSD.