Disallowance U/s 409a) (ia)

I have Two question.

1) If A is partnership Firm & Tax Audit is applicable for F Y 09-10.

If Labour payment has been paid to Mr Y . Details are as follows :

Rs 18000/-  05.05.09

Rs 18000/- 05.10.09

Rs 18000/-05.03.10

Total 54000/-

Then on which amount TDS should be deducted? on Rs 54000/- or 4000/-

2)  If Labour payment has been paid to Mr Z . Details are as follows :

Rs 25000/-  Paid on 30.04.09

Rs 100000/- Paid on 30.09.09.

Rs 75000/- Payable on 31.03.10.

But in this case , A has not deducted TDS on such expenses.

As per provision u/s 40(a)(ia) , which amount will be disallowed , means Rs 75000/- ( payable amount ) or total amount.

Please any one explain me

Thanks