USA Recognition of sale involving a future contingent consideration

[KRag]

An internet based company is having a promotion where customers are invoiced $400 for installation and a monthly fee thereafter. If the customer pays 6 consecutive payments towards the monthly bills they will be exempt from the $400 install fee. How is the $400 recognized in the books initially?

 

[Counterofbeans]

Please elaborate on the cash flows in your example. Has the customer paid the $400 yet? Does this company actually invoice them for said $400? Other?