payment in advance (at the start of the transaction)


	avoids any possiblity of providing the service and then finding that the client does not have the money to pay for it

	avoids any possiblity of providing the service and finding that there was a misunderstanding about the price

	not practical in some circumstances where the cost is not known at the start (alternatives, 20% deposit in advance etc).

	simpler admininstration



e.g. retail products




payment in arears (end of transaction)

	allows the exact amount to the paid

	relevant when several items may be ordered

	may necessitate creating a rule involving cancelling the transaction if the client does not return for an extended period of time

	


e.g
	
hotels, restaurants, regular supplies etc.

