Interest on tds

No Interest on TDS to be paid on earlier payments which will you now deduct.

as if u deduct tds late then interest liability arises but on earlier bill there was no tds liability so que of interest not arises.. 

Liability to make TDS arises only when limit prescribed under the Act i.e. Rs. 30,000/- is exceeded. Till that time there is no liability of TDS. However once the limit is exceeded then you'll have to make TDS on whole amount. like in your case you'll have to now make TDS on Rs.33000 + amount of earlier bills. If you do so there is no liability of interest.

If the aggregate amount of payment made/credited or likely to be paid/credited does not exceed Rs.30,000/- in a financial year (from 1.7.2010). It was Rs.20000 previously.

So the time you have crossed the aggregate limit of Rs 30,000/-,you will have to deduct TDS on the earlier Bills on the same date and pay the some till the upcoming Due date of payment of T.D.S.

and If you have not paid the above TDS on the Due Date ,then you will be charged Interest @ 1.5.%p.m,as the case may be.

The Liablity to Deduct Tds arise when u Reached to said Amount as in ur case is 30000/- but when u had raised the Bill amounting crossing the limit , then u have to deduct the tds on whole amount pertaining to that F.Y. . There is no need to pay Interest on Tds as at that time u were not liable