Disability deduction under income tax provides a standardized, severity based allowance for certified resident individuals with disabilities. Section 80U provides a flat deduction to resident individuals certified by prescribed medical authorities as persons with disability (minimum 40% disability), with a higher standardized allowance for severe disability; the deduction is independent of actual expenses. Claiming requires furnishing the prescribed disability certificate with the return, and a time limited certificate must be renewed for subsequent assessment years. The provision is limited to resident individuals and is distinct from the deduction available for dependents.