Avoidance of repetitive appeals: declaration allows applying a final decision in a related tax case, barring re litigation. An assessee may submit a prescribed verified declaration claiming an identical question of law in two income tax proceedings; the assessing officer or appellate authority may admit or reject the claim after obtaining the assessing officer's report and hearing, may dispose of the relevant case without awaiting the other case's final decision, and must apply that final decision to the relevant case when it becomes final; orders on the claim are final and not subject to appeal, reference or revision.