Form26as - tds from fd not considered while filing itreturns

Hi,

I have some FD's and due to which TDS of Rs.5000 was deducted by Bank and the same is reflected in my Form26AS (Financial year - 2013-14).

I was not knowing about this and hence I didn't file income tax for the income from FD interest.

I come under 30% income tax slab. As bank has deducted 10% as TDS, I think I need to pay 20% of FD interest as income tax.

I have following 2 queries,

1. As I have already filed IT returns for financial year 2013-14, how can I pay the 20% tax (on FD interest) that I have missed to pay?
2. Do I need to pay any penalty?

Thanks in advance,

Vinod Kumar M J