I was recently asked to participate consultatively in the project of creating an independent purchasing department that will support and process all purchasing needs of the Sales & Marketing dept only.
The procedure will be that all S&M dept’s requests will be forwarded to the Purchasing Dept through a Purchase Requisition Form, signed by the appropriate representatives of S&M dept. (the estimated and budgeted cost will be presented in the form).
Then the purchasing dept. should proceed with the bidding procedure, select the suppliers and complete the Expenditure Request.
My question is: who do you think should sign and approve the Expenditure Request? Only the Purchasing Dept (as an independent dept) or signatories from both the departments (since the S&M dept is the budget holder)?

Thank you

S&M's approval up to the estimated amount already exists on the Purchase Requisition Form. The only time Purchasing should go back to them is when the bids come in a certain % above that amount. They should work together to decide how far above the estimate is reasonable. 1%, 5%, 10%, etc.

Signing the Expenditure Request is the responsibility of Purchasing with a copy to the S&M group.

I've known some S&M groups that act like they are into S&M!