It will be allowed. Eg:
in 2005-06 Rs.10,000/- - TDS 10%, then TDS is Rs.1,000/-
Now, you have paid the amount from your Pocket. But how much have you paid as TDS in 2006-07.
Case 1: - Rs.1,000/- and this payment is debited to Expenses A/c
As rightly pointed by G.K., Rs.10,000 wil be allowed but not Rs.1,000/-
Case 2: Rs.1,000/- payment is debited to party's account as recoverable from him
Same as above, but there is no concept of disallowing the same, as the extra Rs.1,000/- was not claimed as expense in the first place.
Now, you have two options,
a) Collect this amount from him / recover from next bill
b) Wait for some 1 year or so and write off as Bad Debts, you MIGHT Get away.
Case 3:
As you have already paid Rs.10,000/- - this amount is treated as an after tds amount
In this case, If Amount is 100%, then TDS is 10%, after tax amount is 90%,
So equating 90% to 10,000/-, you will get 100% as Rs.11,111/-
Now pay Rs.1,111/- as TDS and Debit the Expenses account, you will get full credit
Good Luck
Shiva