Sec 234 A is paid for delay in payment of Tax beyond the due date of filling return. ( 31st July for Individual, 31st Oct for companies ).
It has to be paid @ 1% P.M. for months exceding the due date for filling. Suppose Total tax due 10,000 for Individual as on 31st July 2007 and tax paid on 5th Nov'07. Den total interest under Sec 234 A will be 10,000*1% *5.
TDS deducted should be adjusted before calculating the total tax due.