If you are a company and a person who is liable to pay the vendor for the service he has provided you, then you are responsible to deduct and deposit part of the money towards TDS on the name of your service provider to Government. At the end of the financial year you are responsible to issue a tax certificate to all the vendors, freelancers, and employees called form 16 for them to submit and claim their TDS refund if any. 

1. TAN number

2. Tax paid receipt

3. Details of tax deducted

4. Details of supplies

1. To avoid penalty
2. To reconcile the ITRs
3. Avoid cancellation of expenditure