What are the types of discounts that can be done in subcontractor payment?

Discounts in Payment? I think you want to mention deductions in payment.

1) Advance Payment Recovery

2) Retention

3) Deduction due to bad quality

4) Deduction due clearance

5) Deduction as penalty

Discounts can be of various types depending upon the volume of business that one does and the fund requirements. In case of immediate liquidity, cash discount can be offered to clients. In case of increasing sales, volume discounts can be offered to clients and in case of luring more customers, referral incentives can be offered to existing clients etc. It all depends upon the nature of business and cash flow of the company.

Advanced payment, deduction due clearance, deduction due to bad quality & defective products, penalty settlement and retention etc..

*All of which are depend on the internal procedures and policies of each company.

Purchase order (PO) ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

The best discount when the customer to pay in advance and when the goods were not required or the implementation process as required

I agree with Eng. Imran Ahmed.

and all what he said should be with the addition to " previous payment discount" ofcourse.