Deduction under 80GG: individuals paying rent must submit Form 12BA to claim a rent deduction.
An individual who pays rent for residential accommodation may claim deduction in respect of rent paid provided the claimant submits a written declaration in Form 12BA to the assessing officer asserting entitlement; the deduction is contingent on both actual rent payment and timely submission of the prescribed declaration.

Deduction under Section 80GG determined as the least of three statutory measures; example illustrates rent-based cap applies.
Deduction under Section 80GG is the least of: (1) Rs. 2,000 per month (Rs. 24,000 per annum); (2) rent paid less 10% of total income; and (3) 25% of total income. In the supplied example with total income of Rs. 3,00,000 and rent paid Rs. 1,50,000, the three measures are Rs. 24,000; Rs. 1,20,000; and Rs. 75,000 respectively, so Rs. 24,000 is the allowable deduction under the prescribed formula.