Ppf interest not shown in income tax return

Dear Experts

Mr. X was depositing some amount in his PPF account annually and he was earning interest on PPF. But he failed to show interest earned on PPF in his income tax return.

What are the consequences for the above failure?

He had deposited total Rs. 10 Lakhs in PPF and interest thereon amounted to Rs. 250000.

Now when he withdraws all the amount from his PPF account i.e Rs. 12.5 Lakhs, What will be the tax implications?