contract
invoice
receipt document
the account bank of the other party
1. Purchasing is generally a VAT invoice or an ordinary invoice. If your company is the last consumer, it is not necessary to be a VAT invoice
2. If it is the first time to make an account and pay, then the contract is definitely necessary, and generally speaking, it is also necessary. Contracts and warehousing documents, as long as you explain when the account was made and what progress you need to pay now
3. Depending on the situation
4. Looking at the company's internal system, it is generally necessary for the manager himself, the manager of the handling department, the manager of the financial department, and the financial manager, and if the amount is large, the person in charge of the company
5. You can ask for a bank receipt in the name of the customer
Supplement: < Some companies are the same, while others are different.
6. Generally, all companies should be filled in. If the company system is not so strict, some companies will pay directly according to the contract schedule, then the purchase will be ignored.