Tds interest

Yes you need to deduct tax for the whole amount including previous bills. 

It is unfortunate but you have to pay interest on late deduction.

Natesh

As per my knowledge, if limits crossed in January, and TDS deducted for the biils from April to January (current bill) and TDS deposited at right time, then no interest or fine will be applicable.

Because deductor have no idea that limit will be crossed or not till January bill.

If i am wrong please correct me.....

Thanks

You have to deduct TDS on full amount (including prev bills of financial year) but you need not to pay interest on deposit of the same. Interest has to be paid if (i) TDS is not deposited after deduction or (ii) TDS is not deducted as per rules. In first case you have not failed to deposit the TDS after deuction because you have not deducted the same. In second case you was not liable to deduct the TDS since the amount was under the ceiling limit. Therefore, you are not liable to pay the interest.

Please note that it is assumed that since begining of the year you was not having any estimate that the ceiling limit will exceed during the year.