Section 20B(6) in The Slum Areas (Improvement And Clearance) Act, 1956
(6)Where the rent is finally determined under this section, then the amount of rent paid by the tenant shall be adjusted against the rent so finally determined and if the amount so paid falls short of, or is in excess of the rent finally determined, the tenant shall pay the deficiency, or be entitled to a refund, as the case may be.