Wouldn't these be inventory items?  Handled the same as buying and selling buggy whips, except the seller is the customer who pays down the debt.  

It isn't clear if your client has Factored (sold) the receivables, which typically is a type of secured debt (liability). Or, your client Bought them (an asset) and will be collecting later (is the factoring agent).

On second thought, my mistake was to assume the question was about purchase of receivables, when it probably involves sale of receivables.  

Anyone interested in buying my accounts payable?  

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@BobKamman wrote:

Anyone interested in buying my accounts payable?  

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what about a like kind exchange