A clause in a lease providing for an increased rental at a future time. May be accomplished by several types of clauses, such as (1) Fixed increase - A clause which calls for a definite, periodic rental increase. (2) Cost of living - A clause which ties the rent to a government cost of living index, with periodic adjustments as the index changes. (3) Direct expense - The rent is adjusted according to changes in the expenses of the property paid by the lessor, such as tax increases, increased maintenance costs, etc.