You are allowed to claim extra deductions subject to income tax filing, in case you forgot to do so in the first place. (policybazaar.com)
On home loans, most people look at the deductible amount of their interest, but they neglect to look at the fact that they can deduct a good chunk of that anyway via the standard deduction — their actual extra deduction due to their house is often much smaller than they might think. (thesimpledollar.com)
It was claimed that the extra deduction was required to cover administration costs. (money.stackexchange.com)