Downward revision of S.A. means reduction of Sum Assured.
For example: (Assumption only)
Age 37 year
Term 10 Yrs
Plan - Jeevan Anand
S. A - 1,00,000/-
Premium is Rs. 9000/-
For S.A. 50,000/-
Premium would be Rs. 4500/-
It would be noticed from above example that the premium reduces with reduction in Sum Assured (S.A.) as premium is directly proportionate to S.A.