Deduction of TDS for foreign company

Dear All,

TDS to be deducted for the payment made to foreign company for their services. pls clarify below mentioned points.

1. When TDS has to be deducted for payments covered under Sec. 115A (1)(b) : at the time of Booking of expenses or at the time of payments.

2.Time limit to deposit the TDS.

3 Prescribed form to issue TDS certificate to the foreign company.