Section 87 a of income tax rules

Section 87 A mentioned that the persons having "total income" not exceeding Rs. 500000/-. I doubt that the income should be considered before deducting deductions u/s 80C, but many experts are of the opinion that it will be deducted after deduction u/s 80C i.e. from "taxable income". I am confused by the words "Total Income" and "Taxable Income". Please someone help me and clarify by quoting rules etc..

Thanks