Tds on advance payment

As per TDS rules "TDS is applicable on Bill or Payment Whichever is Earlier"

In your case Payment is Earlier, than you have to Deduct TDS on Advance Payment.

But if you had made full payment than calculate TDS on full payment and subsequently adjust in Ledger.

i.g.:

Adv. Payment is 100000/- for 94C

than make Payment of 1000/- as TDS and when in future bill of Rs. 200000/- is submitted by you contractor than do TDS deduction on Balance Rs,100000/- for Rs.1000/- and Make a cheque of Rs.98000/-